What kind of video can I edit?

I am interested in working with this package. However, I do not have bought a camcorder yet. So I need to know if I can import like DVD movies into this program, directly or via another application.

Or if there are tutorials with practice exercises. I want wait just a few months with buying a camcorder, and would like to master Avid in the meantime, so I can start straight away when I have my camcorder.

So can I practise with Avid without a camcorder?

Thanks for your advice.