Songs for your team

I want to add my own songs to my team so the sounds when they enter the pitch sound more realistic, as well as the fans' own songs. I have tried this but when I start a game i get a message which says it's the wrong file type.
What file type am I supposed to use when doing this?|||mp3 or an audio track ripped from an audio cd|||But I added this song which was mp3 128 kbps and it didn't work...