All the book details only need to be known in depth by the GM. But, if you're with an easy going group, you can just learn as you go. Deathpharaon is right, the game's easy to play when you're with the right people. But stay away from hardcore D&D guys. They'll insist you know almost ALL the rules, and will probably not have much patience to explain them to you all the time. Just need the Player's Handbook, the DM's Guide, and some friends. It really IS kickass.  =D