Good luck with your fitness goals, but from all I've heard, Crossfit is extreme and often dangerous approach to fitness.
I have seen plenty of healthy people that were in good shape go into that program, and find it was too extreme for their needs, or they got injured doing one of their extreme workouts and had to give up exercising for several weeks until they healed.
The on ramp classes are NOTHING compared to what those coaches will expect you to do after you graduate to the regular Crossfit classes. So if you are sore now, it will be MUCH worse if you decide to enroll in the regular classes.
This article from the NY Times has some really good background info on Crossfit. You might want to check it out before you get any more involved with that organization.
Getting Fit, Even If It Kills You
http://www.nytimes.com/2 005/12/22/fashion/thursdaystyle s/22Fitness.html?pagewanted=all 1594 days ago