For information on how to access your client panel, see this article.
In the Client Panel, You can change the music options in the "Settings" tab, by scrolling down to the Music options below the Tour Title option.
You can listen to the music options to find the one that best meets your needs. To listen to the music selections, highlight one of the songs, and press the "Play" button (the triangle). To stop your music, select the "Stop" button (the square).
Once you have chosen a song that you would like to use, highlight the desired choice and scroll down to click on the save button (below the "Statistics Email" box).