If you are looking for just free music you can get it here
If you just need to know how to add it to a tour: Click on "Publish" and then click on the "General" tab and then brouse for the file in the "Background Sound File" field. Remember to check "Loop" if you need it.
If you want to add a voice over for each scene you can do that in the "Properties & Actions" section for each scene in the "Sound:" field.
Nikon D300, D3s, Nikon 10.5 lens, RingT105N+Footplate+MrotatorTCPs, Giottos MT9261 Tripod, Manfrotto 410 Jr geared head.
If you know the "secret" then everyday is a good day!