texture format?

hey guys, i was just trying to edit a few of the effects, and i tried to edit some of the textures. now i have no idea how they're supposed to work. black seems like the transperant color and white the color you see.. bit like an alpha map. but when i make my own version of these, and load the game with them in my mods/tims test mod/textures/ directory it still runs the game, but no textures are visible (skyboxes are gone, menu apears as a white box, planets have halo's visible, nothing else!)

how am i suppose to save or do these files? theres many settings in the dss.