Hello, I love to map all sorts of things but I don't know how to make custom textures so a little help would be appreciated
Try to find some older threads on this. There are dozens of them, for sure. People get bored explaining this kind of problems, over and over again to every single newbie mapper. Nothing personal though... :D
The most important thing you need to know is that a texture should have a proper size: 1024x1024, 512x512, 128x128, 64x64, 32x32... or 1024x512, 64x128 etc. Also, in order for your texture to in work in game, you have to write a shader file - it's basicly a txt file with changed extension to shader, and it contains all information for textures.