That's really easy dude, just do what you did and then put your footage in the source monitor and slide the bar untill the end of the first song , mark it and pull it to the timeline and there you have one song, do the same but for the second song, mark the first point (where the song starts and the second and last point (where the song ends) and dragg it to the second timeline and so on for the rest and then export each timeline as audio and there you have your songs separately .