The best resource to learn more is from the CrossFit HQ site.  Here are a few links to learn the basics:

What is CrossFit?
CrossFit Foundations
What is Fitness? by Coach Greg Glassman
The CrossFit FAQ

And finally, some words to live by:
CrossFit's "Fitness in 100 Words"

"Eat meat and vegetables, nuts and seeds, some fruit, little starch and NO sugar. Keep intake to levels that will support exercise but not body fat. Practice and train major lifts: deadlift, clean, squat, presses, C&J, and snatch. Similarly, master the basics of gymnastics: pull-ups, dips, rope climb, push-ups, sit-ups, presses to handstands, pirouettes, flips, splits, and holds. Bike, run, swim, row, etc, hard and fast. Five or six days per week mix these elements in as many combinations and patterns as creativity will allow. ROUTINE IS THE ENEMY. Keep workouts short and intense. Regularly learn and play new sports!"

Courtesy of CrossFit, Inc.