This diagram illustrates how to fire off a BooTunes with a PicoBoo Jr (103) or PicoBoo (104).  When output 1 is activated the BooTunes will play the input 1 MP3 file.  You can also share output 1 on the PicoBoo with another 12v device such as a solenoid.  However, do not share output 1 with a 110v AC device because that will damage the BooTunes.