Complex sentence: He soon learned of Louis Armstrong, Fats Waller and Duke Ellington through Lawrence Wright's music newspaper "Melody Maker" (which had begun publication in 1926); he chose to focus his enthusiasm on the music of black bands.
Split into simpler sentences: He soon learned of Louis Armstrong, Fats Waller and Duke Ellington through Lawrence Wright's music newspaper "Melody Maker" (which had begun publication in 1926). Dance chose to focus his enthusiasm on the music of black bands.