[dunkelgrun]

The backgrounds are all called 'background.tga'. Find the one you want to replace, e.g. Missions/background.tga and substitute your own. You will have to do some resizing though. Your replacement pic should conform to the proportions of your monitor's resolution, but of all the originals are 1024x1024. Your picture will need 'squashing in' from the sides until it's square.

:cheers:

PS The HSFX background.tga appears to break the size rule, but the game's originals are all 1024x1024 or 512x512.