How do I CREATE a NEW Skin?

I'm sorry for the somewhat obnoxious topic title, but I want to be quite plain what I'm asking about: I am not interested in editing one of Blizzard's skins. I am part of a new-ish (we upgraded from StarCraft) Total Conversion group that will be using Blizzard's 3D Studio Max WarCraft III Art Tools to create new models for our altered units.

However, I just do not understand the "skin" aspect of the models...I understand that skins are textures wrapped around models to give them an outward appearance. What I don't understand is why ALL the textures used by a particlar model are in one .tga file in a wierd sort of collage. I mean, I've taken several 3D Modeling classes and we've always given specific body parts specific textures. How does 3D Max know where to separate the specific items on the .tga file and give them to the proper bodyparts (in other words: what modifiers are used)? Also, is there any particular order these collage .tga files should have their components (Weapons in one spot, heads in the other. etc.)?

Thanks for any help you can give...I'm just bewildered by this style of texturing.

if you want to make a new skin then u have to make a new model with some modeling program

When you make an model in max you have to uwv unwrapp it inorder to place an texture on it. When you uwv it you decide where which mesh parts of the model should be located on the 2d texture. You can unwrap the hole model onto the same uwv space so to spk. I myself have 2 building textures on the same 256x256 space. The buildings are seperated in diffrent max files. I just placed the unwrapped pieces so they both could fit.
Hope this makes some sense. Im not very good at this hole 3d stuff.

No kidding...</sarcasm>

As for the helpful reply from Targash...it looks like I'm going to have to learn how to UVW unwrap. It's something I've never had to do before...