Complex sentence: In his late teens, he moved with his family to Modesto, California, where he attended Grace M. Davis High School and joined the high school jazz band (playing guitar and drums) and marching band (playing snare drum).
Split into simpler sentences: In his late teens, he moved with his family to Modesto, California. Where he attended Grace M. Davis High School and joined the high school jazz band (playing guitar and drums) and marching band (playing snare drum).