Quote from Deadwood:
This is easy to answer.
If want to learn to trade, start trading. Trading isn't learned through a book, it's not learned through simulation, it's learned by first losing money and then figuring out why you lost it.
If your like most people though you'll soon learn that what you need to understand in order to trade successfully isn't the stock market so much as it is fixing all the things that are wrong with you as a person that stop you from winning.
A good understanding of money money would help you though. At least that keeps you in the game long enough to figure out why your screwing up so badly.