What song?

Hello, I was on the school iPads we have for music, and the class is working on a music project where each person is given an iPod with Garageband and you are to make a music piece. Now, I went onto garageband and loaded up my song and when I pressed play, my song was playing, but much louder, was a song with an amazing melody comprised of various synths and instruments. It was the best song I had heard in ages, and I want to know how it was playing and how I can get this song, and I ask on here because I guess it is related to garageband because that is where I heard it from.