Please help

Hey, I was wondering if someone could recommend a couple of books or webpages devoted to piano or guitar. I am learning to play both of them and I don't take lessons. My problem is that most of the sites I learn from just tell you how to read music then teach some chords and scales. This is good and all but my problem is that I know these scales and chords but have no clue what to do with them now. Can anyone recommend a book that can help teach me the chord/scale relationship and how to go into different scales. Any help would be much appreciated.

Thanks

My 2 cents: A few theory lessons will save you about a month of trying to figure out the basics