You're now going to improvise off the main melodies. To start with, play the a melody regularly once and then the second time through, improvise around the main melody. One, two. Ready, go. Now you're going to do the same thing. With the B section of our melody, play the melody once normally and then improvise around the melody the second time.

Now try improvising freely over both sections, choosing to either use some of the melody or make up your own part completely. One, two, ready go.