First, cut the conduit to the desired length. I made mine 4'8", but you can make them any length you like.
The tubing cutter has little rollers and a cutting wheel on a clamp. Tighten the clamp onto the conduit where you want the cut then tighten it down, turn, and repeat until the conduit is cut all the way through.
A hacksaw may also be used to do the job.
If you don't have a way to cut the conduit, the hardware store may cut it for you when you buy it.