As I teach myself to play piano, what theory do I need to know?I had a few years of piano lessons when I was a kid, and I can play major and minor scales and chords. I know that songs often progress in 1/4/5 (like C/F/G or G/C/D). I don’t know anything about 5ths, 7ths, 9ths, add 2s, etc. I can figure out how to play these chords by looking them up on YouTube, but I don’t know what they mean or how they fit into songs or chord progressions. My goal is to learn to play musical theater accompaniment (songs like “For Now” from Avenue Q and “I’m Dead” by Randy Newman), as well as rock songs like “Miss Misery” by Elliott Smith and “Nobody Home” by Pink Floyd. Eventually I would like to try composing. Besides trying to figure out these songs by ear and possibly getting the sheet music, how should approach learning to play? What theory do I need to know that would help me as I begin to learn?
Any thoughts or suggestions welcome.