I think you'll find that there are some great streaming video tutorials that explain this much better than the spoken word. The program manual also covers this (Help >> Display Program Manual). Videos are located
via this link.
The one that I'd start with is about 1/2 way down the page and is called, "Band In A Box 2007.5: Editable Notation". Because the development of BIAB is additive, what you can do in 2007.5 is still pretty much the same in 2010.
Regards,
Noel