I want to create a project where I can push a button on one device and wirelessly have another device play a sound. Any ideas on how I can do this?
I suggest that you get a copy of the "Arduino Cookbook" by Michael Margolis and get acquainted with his circuits and sketch examples. Later in his book, he has some examples of how to control devices wirelessly, including using a transmitter or an XBEE shield.
Sounds like a fun project. Good luck!