I get some of my information from our corporate office since we are not provately owned. That helped me a lot when I was new. I am a member of AANAC but have not been certified yet. They have a lot of very helpful information. It is expensive, somewhat, if you decide to join AANAC. About $100. But I find it well worth it. I've also noticed on many of the MDS job postings lately (for instance on CareerBuilders.com) that they are requiring AANAC certification. That should say something for them I suppose. The free subscription for AANAC is about to end, unfortunately. If you can afford it, or your company will pay for it, I think it's well worth it to join. You get helpful information from experts in MDS. I've also seen a really nice tutorial on the CMS website but I don't have the link. I'll see if I can find it and update you later. It's really good for beginners.
Good luck!
Janice