I need help, how do i make those things like 'black50.pgn' and stuff and how will it know witch color goes where?
Those textures should be included with other add-ons that came with the game (like the weapon_gun and weapon_rocketL)
And the answer to your second question is, it won't. Do the following:
1- Make a folder, name it the final name you'll be giving to your add-on, like weapon_grenadelauncher (not case sensitive so go ahead and put caps wherever)
2- Put the textures mentioned in the first post in that folder, or atleast the ones you plan on using.
3- Go in MS3D, flatshade, yada yada yada, then assign the textures to your model FROM the folder you just made up. From here on, don't change the folder name.
4- Extract your model, put it in the folder, then put all the other ressources you need in the folder and zip it up properly.
The point is, the model does not save the texture itself, rather it saves the LOCATION. Changing the name of the location will undoubtedly cause your model to fail to locate the texture, and no texture will be loaded in-game.