Electronics stores will often have books on how to make things with beginner projects, I have seena how to make a wah article before. I'm sure that simply reading a couple of books will give you an idea as to wiring diagrams, but something that might be easier to lear from someone else would be how to solder, which is a fairly important skill, and you might not be able to get the hang of it from boos. Once you learn that sort of stuff, it might be a good idea to start on something smaller, like adding a new pickup to an older guitar, or just taking one off and putting it back on, for the practice before you get to mmaking amps.