Start: Load the bar with relatively light plates, and grab it with a full, overhand, shoulder-width grip. Stand, press it over your and hold it there with straight arms.
Finish: Shrug your shoulders up toward your ears. Pause, then slowly return to the starting position. It's a very short range of motion. If you can't feel your traps working at first. Try it again with a lighter weight. If it's too heavy, you won't get any range of motion.