This is a great move for your shoulders. The shoulder is a very important muscle that really gives great shape to your arms. Stand with arms straight and dumbbells in each hand. Lift your elbows straight up, bringing your hands to your chest. Your wrists may turn a little. Lower your hands until your arms are straight, and repeat. Use a weight that allows you to fatigue at rep 10. Try to do 3 sets of this.
Here is an instructional video for this move.