how do i create a cam system? i wanna move aclaw up and down

So you want to translate the vex motor’s rotational motion into horizontal motion? There are several waays you could accomplish this. The one that is foremost in my mind is the rack and pinion kit. You could also build something like the mechanism on the Vexplorer claw.

If you are referring to a traditional CAM, Cam - Wikipedia

Then, creating a CAM out of VEX parts will be a bit difficult. You would have to shape one of the plastic gears to achieve the size and curvature of your cam.