Awww glad you're keeping him!! :) I too rescued my mare and was a "newbie" a short 2 1/2 years ago (I've been riding for 4 1/2 years now, was never around horses before then but always loved them and wanted one)! When I got my mare, I had been taking lessons for about 2 years and had half leased my trainer's horse for a few months. I also made sure I had a great network of friends at my barn to help me, knowledgeable trainer, and a great BO! Then I set out and absorbed any info I could on horses in general, training (my horse was also green broke when I got her!), health, grooming, etc etc. Subscribe to a few magazines if you don't already - I have learned a TON of Equus, Horse Illustrated, and Practical Horseman! I have also been a big fan of searching the web, asking questions on forums like this, and reading LOTS of horsey books either from my local library or from the book store.
You'll learn a LOT and you'll find that you'll never STOP learning, but it is definitely possible for a greenie to train/learn with another greenie, as long as the horse is safe and willing which it sounds like he is :) Ask lots of questions and learn from many...you'll find that there are a TON of opinions in the horse world and that not every bit of advice is going to work for you/your horse. They're individuals just like us and there are no such things as general blanket statements in the horse world, trust me on that one!
Good luck with your new endeavor and we're all here for you to pick our brains!
"The times when you have seen only one set of footprints in the sand, is when I carried you..."