There's the basic docs I'd recommend, since that can usually be a condensed version of D&D so you're not having to go through things that aren't key to the game.
This link for free D&D docs is compiled through some site, but should be given a quick look through:
In addition, you might find fun podcasts or YouTube videos of people playing D&D.
Last, call Wizards game support. I worked there for 6 months and it was a blast. They will answer any D&D question.
Seven Days a Week
9am - 5pm (Pacific Time)
US/Canada/Mexico: (800) 324-6496
Also, just post the question in here - someone is bound to know it.