Begin exercise in supine position with calf placed directly on the foam roller with both hands supporting body weight. Next, roll the calf across the foam roller from high to low and outside to inside. 

Never perform exercise to the point of pain, but make sure that your muscle is feeling just short of the pain threshold as this will help to establish the best mobility in the muscle tissue. 

Never roll over top of the achilles tendon. 

Repeat in same fashion on the opposite leg.