Complex sentence: James entered the music publishing business as his singing career tapered off, and in 1963 established Northern Songs Ltd., with Beatles John Lennon and Paul McCartney, to publish Lennon and McCartney's original songs.
Split into simpler sentences: James entered the music publishing business as his singing career tapered off. In 1963 Dick James established Northern Songs Ltd., with Beatles John Lennon and Paul McCartney, to publish Lennon and McCartney's original songs.