I think the first step after registering is to join a group - in this case CCA. Once you've joined the group you will see the list of auctions, click on the plus to add. It looks like all of the CCA auctions are in for the year, so make sure you put your items in for the right auction.
If you are also a member of PVAS or any other groups or just want to see what they have in their auctions, you can add those as well and see all auctions in your list at once.
Thanks guys! I have been on the my group auctions page for some time now but have never put anything in the auction. I will give it a go and see what happens.