i'm pretty proficient at the guitar in the styles of folk, rock, and blues, but my understanding of jazz and classical are both lacking. i took some classical lessons in college, but i can just barely read and don't know many songs. same with jazz. i understand modes, although i almost never play in them, and know next to nothing about chord substitution or which scales to play over which chords. mostly, though, i'd like to build up a repertoire in both categories, starting with easy songs and moving to harder songs. where are the best places to learn on the net for each respective field?