you need to have mp3 or wav file with the song - we can not distribute this with our software(because of rights).
Then you just press the 'Clock' sign at the bottom of Moncha window called 'Select synchronizer'. Set to 'Audio'.
Another 'Clock' sign, but with red dot appears. Press this and locate your audio file.
It is recommended to keep the audio files in the same directory as show files(only relative paths will be remembered, so when you copy to another computer, no problem with playing show with music immediately).