Controlling sound loops

I am trying to create a movie that has 3 different background sound loops for the user to choose from as well as an on/off button.

I followed one of the Kirupa tutorials which enabled me to create 3 different buttons that linked to the 3 sound loops in my library. The problem is that I don’t know the actionscript required to stop whatever clip is playing and play the newly selected background sound chosen by the user.

Also I am trying to have one of the loops playing when the movie starts as a default, and also to have a mute button. Any and all help would be greatly appreciated. This may seem to be a simple task, although I haven’t been able to find any tutorials on it.