Like the soundtrack in your picture, it must be based on the main theme of the song. When it's time to play the soundtrack, press the relevant handle with your left hand to play it according to the main theme of the song. Take a look, the first one is a low 6, and the other one is a low 6, which should be played at the same time. The second tonic is alto 3, and the dubbing is 6 (bass) 13, which is a typical minor and chord. It should be played with 3 and 6 (bass) 1 in the main melody.