You can easily add music to your tour by going to Background Music and Narration, selecting a track, and clicking Update:
You can click the checkbox or the green play icon to preview tracks until you find one you like. When you add a track here, that track will play throughout tour, and loop if necessary, if the tour runs longer than the track length. You can also upload your own tracks here, using the Upload Music box, just drag/drop your MP3 file and click Upload.
If you have a longer tour and prefer to have multiple different tracks play, you can use the RTV Radio feature:
Just click and drag as many tracks as you want over to the right, which will create a playlist that plays throughout tour, click “Enable / Disable” switch to green, and then click Update. You can preview tracks by clicking the green play button to the right of each track, which will load it into player up top.