First, go here.
http://www.3dactionplanet.com/hlp/fsdl.shtml Go to The FS tools section, and download the following(in order of importance):
1. DLL Pack
2. VPView(either one, choose between stability and features)
3. TableView
4. Modelview
5. Aniview
Or, just get the DLL pack and the Freespace Kit(includes just about everything.)
Next step, install everything(in any order, doesn't matter.) Fire up TBLview first, just long enough to tell it yes to associate automatically with TBL files. Close TBLview.
Fire up VPView next, tell it to automatically associate with VP files, and go into options. Make sure it has found your Freespace home directory(and thus your VP files.) Use the Open VP file option, and select and open root.vp. You will see a nice organized list, and at the top will be a bunch of table files. To view them, just double click on them. TBLview will open automatically. If you actually want to edit them(and you will.

) then from VPView right click on the TBL file of choice(start with Ships.tbl and Weapons.tbl) Tell it to extract to dir, and use the tree and the buttons at the bottom to create a freespace\data\tables\ directory. Hit OK, and tell it yes when it asks if you want to decode it.
Now, you can actually edit the table file. Use Notepad or Word to open up the TBL file you created. You will see a bunch of text behind semicolons- these are called "remarks" and don't actually affect the table data. If you want to add comments on what you are doing, just type a colon and everything after it on that line will not count. Scroll down, and you will eventually get to the ships/weapons. Each ship or weapon has a whole list of table entries with numbers and/or text, all of which can be changed. For details on what everything does, go to
http://freespace.volitionwatch.com/fs1/mods/ for FS1 mods,
http://freespace.volitionwatch.com/fs2/mods/ for FS2 mods. Almost everything is the same between them, however, so if you know how to do one, it's pretty easy to do the other.
Another thing to remember- when FS looks for files to use for textures, effects, models, table files, etc it looks first for those files in your Data directory, and if it doesn't find them there, it will look in the VP file. In other words, you don't have to change anything in the VP file- you just have your modded copy in the right folder in the Data directory, and that will take precedence over whatever is in the VP. If you wanted to change the Orion texture, for example, you could find the texture it uses in the other VP file, export it out(right click on it and export,) change colors and appearance, and put it in your data\maps folder. It's amazingly easy and simple, and I can't wait to see what amazing new ideas you manage to come up with.

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Sushi- the OTHER white meat!