It takes three steps. One: choose your tonal center — spin the circle of fifths, or let an emotion pick the key for you. Two: build your harmony. Browse progressions by genre, spice things up with secondary dominants and borrowed chords, shape your verse, chorus or bridge across three complexity levels, and even modulate mid-song — with a built-in advisor telling you how commercial or adventurous each choice sounds. Three: assemble your chord line and press play — as full blocks or as an arpeggio, in the meter you choose, with real voice leading so every change sounds smooth. Everything you click, you hear instantly. That's the whole point.