Hold the weight in your right hand, palm facing to the sky. Hold this hand above, and slightly behind your right shoulder. Use your left hand to stabilise your elbow (hold it firmly in place to isolate the triceps muscle). Raise your hand up so that the weight is vertically above your elbow, without moving your elbow and then lower slowly. I’m alternating between lower and upper body exercises weekly for the moment.
Check out my Massage Therapy page for the associated stretch for this muscle.