Learning to read music can add to your enjoyment of playing guitar. You can pick out the tune to anything if you know how. Forget having to know a song before you can sing it. I like How To Read Sheet Music (http://readsheetmusic.info/basics_of_counting_rhythms.shtml). Just take it slowly. You’re learning to read hieroglyphics here, not a new language. The pages are deceptively short. Each one should take you quite a while to master. Don’t move on until you know the last one cold.