Richard1

This is probably a quite random question, and maybe not even the right place to post. I'll ask anyway and hope it is. I'm a self-taught guitar player (and not a very good one) but in terms of song writing, I've always be interested in the structure. The main thing I don't understand is layering of different parts. Say you had a guitar playing a B5 chord which was distorted (slightly punk/rock style), and then you had a guitar riff over it. What notes can be used in the guitar riff? Do they have to relate to the B5 chord and match some sort of key? Any answers are really appreciated, I hope I haven't asked it too confusingly.