Begin in a seated position on the floor with your legs stretched out in front of you.
Place the on top of your ankles. Extend your hands out and push the ball out, towards your ankles.
Now, pull your toes towards you while keeping pressure on it with your hands, feel the contraction, hold for a few seconds then release your ankles back down.
Tips
Be sure to not move any other muscles such as your legs or core, concentrate on focusing on your calf muscles.