Use the music slider to select a song, and the play and stop buttons to start and stop music. To change the background color, use the background color slider to select a color, then click the star button to apply it. You can adjust the volume with the volume slider and toggle party mode by clicking the candy.
This is a remake of a project I made on my old account, with more options, more music, more effects, and better code. I unshared this project a while ago because I didn't like the way it looked, so I took some time to give it a major face-lift, and I think it was worth it. All music by Hal Laboratories.