Have you tried the Apple tutorials?
I don't know what software you have but here is an example of the tutorials available for iMovie 11:
http://support.apple.com/videos/#imovie
There are similar tutorials available for other Apple software such as iDVD.
You may also just Google "learning iMovie", "learning iDVD", etc. There's a lot of information out there on learning these products.
Try the local Apple user's club.
http://www.thevillagesmug.org/
Last - most Apple stores offer classes to learn how to use Macs and Apple software.