1. Write down the chords of the music (1 measure for each cell and use "|" to separate chords if there are more than 1 chord for a measure/cell)
Example chords: Cmaj7, Daug7, Bbm7b5, F#mM7, etc.
2. Click on the add-on and press the "Format" button to format the chord changes and generate a link to the backing track.