Think of just about any physical activity, for example swinging a baseball bat. You're doing it with your arms so it's an arm event right? No wait, with out good hip rotation I won't hit past the infield. Oh, and legs, I have to have strong legs to push against the ground to power my hips. Oh wait, core strength, I need a strong core to attach the power from my legs and hips into my arms. Finally we have some arm involvement, but not until after the rest of my body created the power for my arms to channel ito the ball through the bat. Any failures along the way tubes the swing and yoiu got nothing.
Run through a list of other physical expressions of power, speed, strength or whatever and you will find that NONE OF THEM work your body in isolation. The body building model of lifting for different body parts on different days is a failed model for athleticism and is not the CrossFit way. Abandon it.
CrossFit is about three things...Functional exercise executed at very high intensity and with such great Variety you never get in a rut. Functionality, Intensity and Variety that is the secret to CF success.
Here are the notes from the November seminar in Golden, Colorado...lot's of questions answered there.
Did you do Fran as prescribed with 95 lbs? Ten minutes is not bad at all but will drop rapidly as your pullups improve. It's the thrusters that kill me.
Look into the Zone for more improvement on your diet, read Foundations and What is Fitness and go through those notes.
Come back with more questions.