It's confusing to get started in modding and a lot of forum advice might be dated and incorrect.  Just getting started can be disheartening so I thought I'd provide an overview not so much as, "How to mod" but more along the line of, "What's involved and where can I start?".  To that end, here is this post. 

I am not responsible for any mental distress or injury that may result from trying to understand modding.  Read at your own risk.

REFERENCE FILES & CONVERSION TOOLS

You have to be able to read the files before you can mod them and that means if they are in BIN format converting them to TXT. I'd strongly advise visiting MyFist0's weebly site for batch converter files.  This let's you convert more than a file at a time.  Each version of Sins needs it's own converter too. Harpo makes and updates a set of tools you will definitely need or at least want to see and has all the converters.  They let you convert files, update mods between game versions, etc.  His thread and download link is here: Harpo's Tools.

Harpo also has update reference files already converted to text format.  They can be found here.  The reference files included in the expansions up to Diplomacy are completely out-of-date which is why Harpo's are so useful.

ERRR....SO WHAT EXACTLY IS A MOD?

A mod is nothing more than a directory--a folder with other folders or files inside it.  MyFist0 has made a very detailed post on installing a mod here.  If you look carefully, you'll also get a clue on where to paste your own mods in when you're ready to test them. 

You can even make a simple mod right now.  Create a folder called "MyMod" on your desktop. Open it and create a folder inside it called, GameInfo. Next, open your Sins game directory (which is organized exactly how your mod will be organized).  Open the GameInfo folder and copy (don't move) two of the ship files from one of your races and paste them into the GameInfo folder of your "MyMod".  Right click on the files and select, "rename" and switch the names of the files.  Then follow MyFist0's directions above and install your mod.  If you chose say, FrigateTechScout.entity and FrigateTechLight.entity, the next time you play the game, you scouts will be light frigates and your light frigates will be scouts.

The reason you use a mod is because if you just went in and changed the folders, the "checksum" will fail for online play and you won't be able to play online anymore.  Worse, if you made a mistake and changed the original files, you could break the game completely and have to uninstall and reinstall it to fix the problem.  Mods are safe and you can do anything with them--without messing your game up for good.  Mods will not let you "cheat" in online play.  Only people using the same mod can play together.

THE MOD TEMPLATE

Unfortunately, really changing things gets a lot more complicated than the example above.  To do this, the best place to start is with a clean, updated mod template (example).  Fortunately, Zombie did a good job of making a 6-race mod with the work already done up to version 1.32 of Diplomacy (the last release).  It just duplicates factions using what's already in the game.  The added races are Race1, Race2 and Race3--so it's easy to go look at his files and find those things to know what needs to be changed.  Also, follow Zombie's instructions on how to install his mod as you will be changing both Entrenchment and Diplomacy with it..

Here's the link: Zombie's Add a Race 

For the files you can edit in notepad, just use the "find" feature in your text editor and type in "Race1"--then you can go through line-by-line and find every entry for that faction. It's best to start with one area and finish it rather than jumping back and forth--at least until you are really comfortable.

TEXT EDITING

Sins is very intolerant of typos.  If you miss a space, add a period or something ever-so-slight, you can make things not work.  This usually shows with dev error pop-ups (if you're using the Dev mode to play-test) or minidumps if things have especially gone wrong.

There is a more capable text editor you can get online for free that will let you do some things better than notepad--particularly when you are trying to find a line error the developer's versions shows you.  It's called Notepad++ and is free here: Notepad++.  It might take a little while to get the hang off but even if you only use it for line entry searching it's great.

Notepad++ will let you compare two files side by side but it's a pain in the butt to find out how so for that you can download one of several other programs.

• Compare It! ...as a paid version but you can keep using it.
• Beyond Compare...lets you use it for free 30 days (each day used counts as a day).
• WinDiff...is free to use but has more powerful paid versions.

Any will work but the paid ones have more features.  Basically, you can open the regular game file and your same mod file and compare them with the differences highlighted for you by the program.  A good way to catch mistakes.

DEVELOPER'S BUILD & DEBUG

In-game, you can choose to have the mod path shown so you know how to find your mod files as well as where to put them.  In that same directory are your Debug files showing errors, ScreenShot where your screen shots from in-game are stored and saved/recorded games, Galaxy Forge maps, etc., etc.

To start de-bugging your mods as you run them in Sins, use the Developer's build (look inside your Sins directory and you'll find the .exe there.  For a neat list of all the incredible things you can do with the developer's build, check GoaFan's dev guide that I personally dictated to him and insisted he write.  In the same directory where your mod's are kept (AppData) you will find a folder titled, Debug which not only will show all the errors in your game so you know where to look for what you may have done wrong in your mod. Typical locations for the debug folder (Windows 7 and Vista) are below:

C:\Users\<username>\AppData\Local\Ironclad Games\Sins of a Solar Empire\Debug

NEEDFUL THINGS

Another little program that takes up almost no space, uses practically no resources and is total free and not buggy is called DeskPins and it is just all around handy for making sure one window stays on top while you work and are changing back and forth between files.  Here's the link: DeskPins

REALLY HARDCORE STUFF

Zombie has the best (meaning most powerful and versatile) mod editing tool for the game--hands down.  Zombie is also a developer (what the bible refers to as "The Devil") in real life and is amused that lesser beings find his tool hard to learn.  For a guy with a wife and kids he offers a ton of help and he has documented the heck out of this.  Even with his documentation and help though I would liken understanding how to use his Eclipse tool to this cartoon:

It's a beautiful but simple language...you just have to know the Incan monkey god.  To be fair, he's bent over backwards to make this usable and has done a perfect job of thoroughly documenting it.  Highly recommended.  Learn this and all that is Sins is within your power.  For those with busy real lives and no coding background or monkey god connections...good luck.  On a final note, Zombie sounds exactly like "Leonard" on the TV show, The Big Bang Theory.  You really must hear him talk at least once before you die.  My wife laughed so hard she had to go to the bathroom.  It's eerie.

MODELING, TEXTURING , GRAPHICS & EFFECTS

I'm not going into modeling, texturing and the like here as there are very detailed posts all over the forums on this and a lot is involved.  I will say, if you get comfortable with Softimage's Mod Tool  you'll have it made for exporting XSI models to convert to mesh for Sins.  It's a free program but a long slow download and is only 32-bit compatible.  I can't use it in Windows 7 on my computer--though others can on theirs. Otherwise, try Wings3D or Blender (if you already understand it).  Beware...Blender also needs the monkey god connection if you have no modeling background.  Wings3D is your best shot.  If you have a copy of Milkshape, it can do just about everything except the XSI exporter exports version 3.0 and you want XSI 3.5 or higher to make Sins meshes.  Milkshape has a trial but, alas, costs money to keep using. Wings3D is free (so is Blender) and the easiest of them.

If you are a 3DS MAX (or it's related prodcuts) user, there is a model exporter linked here.

Google's Sketchup (free version or pro) can also be used for part of your modeling--though you'll have to learn how to export and convert files from it.  I'm not covering it here in depth but Sketchup exports 3D models as .kmz files.  Change the .kmz to .zip and you can open them as that file type.  The .dae file inside is your mesh that can then be converted to a file you can use (.obj is a good choice) by the free program Meshlab.

Doing textures and graphics for the game will require TGA, DDS and mipmap and bump map things.  Look for forum posts on these but supposedly the best all-around tool for graphics in Sins is Gimp.  It's completely free.   Some plug-ins might be needed.  Again, check the forums.  Zombie has a really good XSI tutorial video here that's worth watching and re-watching as you learn:

Finally, KrdaxDrkrun has made a thread specifically on Particle Forge (the Ironclad program that lets you make explosions and pretty sparkly things).  You can find his official thread here: Particle Forge Help

MESH FILES & RIGGING POINTS

The mesh files used by Sins once converted from BIN to TXT can be edited in notepad or any text editor.  So even new modder's can play with and learn by moving around weapon and ability points, exhaust effect points and the like.

SOUNDS

Finally, to edit sounds, the simplest and easiest tool to use is Audacity...which also, thank God, is free.  If you are a real sound maniac and want to play around in mind-numbing ways, there's the paid program GoldWave (not to be confused with Goldfrapp):

GoldWave's a great investment for anyone who needs to regularly convert quality sound files using a pc.  On the adventurous and "No--I will not help you here side" you can try pre-recording mixes with the free and excellent FMOD Sound Designer which lets you make custom sounds for games including 3D modeling effects, etc.

MOVIE INTROS

Finally, if you want a quick way just to watch the Sins movies--or view your own to make sure they'll work in game, there's another free tool called Bink & Smacker (no kidding) in the Rad Video Tools download.

Good luck future nutcase.  Make something and they'll call you a modder.  Begging for people to do your mod for you doesn't count.  Trust me--it's been tried.

POSTING TEXT FILES ONLINE

If you need to share text from inside your files, use Pastebin which lets you upload it with a link to read it with online. It keeps your forum posts easier to read and helps stop the thread from getting lost in the clutter of super long posts of boring file contents that might not even be done right.

GETTING ACTUAL MOD-MAKING (MODDING) HELP

The "big brother" to this thread is the actual modding help thread.  If you are actually WORKING on a mod, you can find links and ask for help here: Modder's Get-An-Answer thread.

P.S "Working on a mod" doesn't mean, "I'm trying to install one"--it means you are trying to make a mod yourself.

Good Luck.  If nothing else works, be sure to blame Ryat.