MasterofDisaster,
you can use any program you want to actually draw what you will see of the skin in game, but you need a program like photoshop to convert it to 32bit. MS paint only saves in 24bit. 32bit is like a hidden layer in grayscale. It's used to decide which part of the skin is totally invisible\partially visible etc. Warcraft III viewer can add a blank version of this layer to a regular JPEG, but i don't think that usually makes it works for warcraft
To make the story short you gotta find a program that can open\edit\save in 32bit. TGA and BLP files can be saved in 32 bit, but a TGA can also be in 24 so you gotta check |