How do you get the music to play on 107.7

A song is played in the Light o Rama program where the sound comes out of the sound card. I could hook up speakers in the yard and run cable back to the computer but that wouldn't be as fun. Besides I don't think the neighbors would appreciate hearing the music all the time. So instead I use a Whole House Transmitter set to FM 107.7. There is a 3 ft wire antenna attached to the transmitter which is attached to the rain gutter above the garage.