Go to the Subrosian Dance Hall and play until you win the flute. Get a ride from Ricky (see Hint: Getting Ricky). When you drain the water from the floodgate, go down until you see an area with a flower and two Spider Tektites. Go down one more screen and go right, and up. You will see Dimitri being attacked by Moblins. Save him and he will teach you his song. If you get the song from the shop, it will not work with Dimitri, or the dance flute for Moosh.