Bnet offer a very good introduction to GTD: How to Get Started with Getting Things Done. First the site design is very good: There is the Web 2.0 style that make the site pleasant. Then the GTD process is summarized in 5 steps (Goals are defined for each steps): 

1. Clear the Decks: GOAL: Record all your commitments to free up mental energy and start accomplishing things. 
2. Empty Your Inbox: Goal: Break tasks down into actionable steps.
3. Feed Your "Trusted System":Goal: Put your action steps into categories where you can review and complete them easily.
4. Repeat Weekly: GOAL: Set aside time each week to review your action lists, so that no items go uncompleted.
5. Get Things Done: GOAL: As small action items move off your lists, contemplate larger projects and life goals. 

And for each steps there are some advices or links to external resources like this list of GTD Tools.