I would suggest you play some online freerolls to get the feel for online poker. If you can deposit (not sure based on the US rules) then I would deposit as much as you are comfortable losing. Dont deposit $200 if you can only really afford $75 for example. Then you need to stick to some strict Bankroll Management.
With regards to books, there are hundreds of books out there that you could learn from. The ones that always crop up are the Harrington on Holdem. There are 3 of them and they are a bit dated, but they will give you a good solid foundation to build upon.
I would also suggest you watch youtube strategy videos and any live poker you can to pick up tips. Then you just need to put in some volume and learn as you go along.
One thing to note is that online play and live play are totally different, you may be really good at live poker but not to good at online, or vice versa. Only you can decide when you are ready in my opinion.
I could write all day giving you things to research to help you improve but you would be better off just reading poker forums such as Two Plus Two and Pocket Fives and of course browsing through this site.
Hope this helps. Gareth