Adding multiple sounds to Powerpoint 2011 for Mac?

We are using Powerpoint 2011 for Mac.

My student is trying to have a song play throughout his presentation, but be able to stop it (or have it stop) at a certain slide. Then he wants to play another recording one just one slide. In the Animations ribbon the “Animation Options” box is totally greyed out, so we can’t mess with the Effect Options.

Any help would be greatly appreciated by both of us! We are going into hour 2 of trying to figure this out.