This area will populate with songs containing the chord progression that you build.
The chords surrounding the chord(s) you chose are the ones that come next most often. The percentage tells you how often.
To continue, click additional chords to modify the chord progression or click any song from the list to view its Theorytab. When you view a Theorytab, chords that are not part of the progression will be darkened to draw attention to the chords you've chosen. The song list is scrollable.