There is an inexpensive book you should obtain -- The Tree Climber's Companion by Jepson. It only costs about $15 and virtually every tree climber owns a copy. It describes all the basic knots and introduces closed hitches.
Just a quick sidenote, we should all receive a commission. I've personally recommended that book on here a bunch of times, and I know a ton of others on here have recommended it as the 'go to book' for anybody just starting out climbing. Makes me wonder how many copies have been sold from us giving free advertisements. Sorry, just saying.
Also, I think SherrillTree's website has a nice list of knots.
http://www.sherrilltree.com/Learning-Center/Knots