If you're still confused, and I wouldn't blame you, there are some files in the3 docs folder in the Dom3 directory. You could also check out the Maps and Mods sub-forum here. I you might get some more detailed info there.
NOZIGAN, just use Wordpad. It should come installed on your computer, assuming you are using Windows. The file you want to edit is the .map file, NOT the .tga file.
Open it up and put in #specstart directives for each nation in your game.
Ironhawk, wordpad will not correctly display a LOT of the .map files used by modders in this game. I don't know why, but it would seem a LOT of folks around here are not running windows systems.
Either wordpad or notepad should be fine. The .map file is a simple text document. It shouldn't matter what sort of system is being run by the creator or the editor. You could probably even uses a full scale word processor like word or open office writer, although I wouldn't reccomend it.
Yeah, I'm not sure what kinds of problems you are running into Panpiper? I've edited plenty of map files and never once had problems getting them to display. Do you want to send me your .map file? Maybe its just corrupt?