Loop the band around a sturdy post that will not move and grasp both handles in one hand.

Stand in a staggered stance with the  left foot forward. Hinge at the hips, so the torso is angled at a 45 degree angle.

Using a supinated (underhand) grip, press the elbow firmly against the ribs. Imagine that the elbow is bolted to the ribs and DO NOT allow it to become unattached during the duration of the exercise. 

Bring the arm to full extension, simply by hinging at the elbow and focusing on the tricep do all of the work.

Flex the tricep for a full second, then allow the forearm to slowly return to the starting position.