I am new to using .wav files. How are these incorporated into my music song files. For example i am experimenting with Band In A Box Music software?

With Band-in-a-Box 2006, you can use the Audio | Import audio… menu item to do import a variety of different audio file types, including MP3, WAV, WMA, and CD Audio. This may be useful if you have a Wave file that you want to add audio harmonies to using the TC-Helicon feature. If you want to add the wave file as a track to your Band-in-a-Box song, note that the wave file would need to have been recorded at a constant tempo, and you’d need to set that tempo in Band-in-a-Box – otherwise the Band-in-a-Box generated tracks will not line up with your wave file.

You can experiment with this technique using any of the free music loops from Partners In Rhyme or use some of the royalty free music collections that come with music loop building blocks to build your own soundtrack.