Ocean walks through building a chord progression in Logic Pro's piano roll, starting from basic scale theory. Play only the white keys and you're in C major (bright, upbeat) or its relative A minor (moody, sad), so picking a scale first means every note you click will fit.
He stacks three notes into a chord, adds a fourth on top for color, then duplicates and shifts the pattern down within the scale to build a second chord. Rearranging the timing turns two chords into a working progression.
To avoid a stiff, programmed feel, he runs Logic's humanize function, which nudges note timing and velocity so a piano part sounds played rather than drawn in.
Selecting all notes and using transpose (option plus up or down) shifts the whole progression into a new key without breaking the chord shapes, and octave-shifting brightens or darkens it instantly.