Yeah just check out that site Pantallica posted. It covers all the basic theory you would need to know about guitar. Make sure you know your scales and chords on the guitar, and how they are structured. Learn the intervals on guitar, like which is a major third and which is a minor third. Stuff like that is what you basically need to know about guitar theory. Then if you want to know more, and I think curiousity is the best way to persue this. Don't do it because you think you need to know it, if you do it do it cause your interested. If not it will be like learning High School History again. But if you do what to step into more advanced stuff, learning how to read and write music is your best move. And just hearing something really cool that someone did, and then just trying to figure out everything you can about why that sounded so kool. That's probably the funniest and easiest way to learn about it, that's all I did. Theory is a instrument for understanding.