No, you don't. I had absolutely no knowledge of music theory when I began playing guitar. I simply learned the chords (only 3 to start with), and progressed from there. As I played more and more, I learned more chords, and eventually learned some (very little) music theory. Today I know hundreds of chords, how to strum, how to finger pick (Travis style), etc., etc. It's been a fun journey. Hope you enjoy it.