Complex sentence: Working as a freelance sign-painter from 1917, he began assembling groups to play for dances, and in 1919 met drummer Sonny Greer from New Jersey who encouraged Ellington's ambition to become a professional musician.
Split into simpler sentences: Working as a freelance sign-painter from 1917, Ellington began assembling groups to play for dances. In 1919 he met drummer Sonny Greer from New Jersey, who encouraged Ellington's ambition to become a professional musician.