This movement works the entire body with a focus on the deltoids and traps. This is an advanced movement that should be performed with caution. The beginning of the movement will work mostly the legs, but as you transition the bar you will begin to work your shoulders, traps, and back to complete the movement.
Begin with the bar on the floor. Set up by putting your feet about half way under the bar, and about shoulder width apart. Next, bend over and grasp the bar with a grip that is just outside of your body. Next, bend through your knees and push your hips back, while keeping your back straight. Now, you want to explosively pull the bar off the floor, and continue to pull the bar up to shoulder height. This is the part that will work your traps, you need to shrug the bar as it comes off the floor. Next, pull your elbows down and under the bar. Also, flip your wrists over so that the bar can rest on your chest. You have now completed the clean portion of the lift.
The press should be thought of as a separate movement from the clean. Now that the bar is resting on your chest, reset your legs so they are underneath you. Now, squat down a couple of inches and then reverse this movement and drive the bar up over your head. Lock your elbows out overhead and you have now completed the movement. Next, reverse the process under control and bring the bar back to the floor to start over.
This is a complicated movement that should be learned in 2 parts with light weights. Begin by learning the clean portion, and then you can work on the press separately. Once, you have mastered both movements you can put the two together. This is an effective full body movement which will increase overall strength.