Soundtrack Pro is software which allows you to create and edit samples of music to the users choosing. Once again the demonstration we were given didn't allow us ample time to understand its features. However, I understand what was required and how to do it. Unfortunately the interface which we was demonstrated on was different from what we had at our own computers. Hence, why we do not have sound and text on our recent videos.
Here's a great tutorial video which does outline the basics: