Measure the length of conduit that you need with a tape measure. Not only do you have to measure vertically to the height of the bend, but you also need to measure the horizontal length to the termination point as well.
Insert the conduit into the tubing bender according to your measurements, then tighten the clamp that holds the straight section of the conduit in place.
Take the handle in your dominant hand while holding the straight end of the conduit to prevent the tubing bender from simply spinning off of your work surface.
Pull the handle toward you while watching the dial readout. This will allow you to bend the tube to precisely the right dimensions. When the tubing is bent to your needs, release the clamp and push the handle of the tubing bender away from the conduit. It does not have a locking mechanism to be removed.