You play a left-hand chord (or send chords via MIDI from a master keyboard). The WK2 automatically generates bass, drums, guitar strums, and pads in real-time. You solo over the top with your right hand.
This is why you buy a "MIDI arranger." The WK2 has (Salsa, 8-Beat, Rock Ballad, Techno, Waltz, etc.) and room for 64 user styles via floppy disk. gem wk2 midi arranger