Okay, probably a really dumb question, but I can't find much on this subject with a google search. What is a CAN?
Commonwealth Assistance Notice. It lists your subjects, their Efstl value and their cost and then if you are deferring to hecs loan. Make sure the subjects are correct otherwise you may end up getting charged incorrectly. Otherwise just file it away. Unless you are paying upfront, or there is something incorrect on it, you don't need to worry about it too much.
Edit: if you are paying upfront then it lists what you need to pay, and payment methods. It also now lists the student and amenities fee. If you are deferring all payments, you don't really need to do anything.