STARTING POSITION:
Select the appropriate resistance in the weight stack. Sit down facing the pulley. There should be a strap that is attached to the lowest level of a pulley. Tie it around your right foot. The cable should have tension before start the exercise.
MOVEMENT:
Fully flex your ankle while you exhale. While your are doing the exercise, move only the ankle, make sure you don't move any other part of your body. Return to the starting position in a smooth movement while you inhale. Repeat the movement for the specified amount of repetitions and then switch sides and repeat with the other arm.
TIPS: The exercise key is quality over quantity. The trick is to perform the exercise using proper form. Make sure you do all the repetitions in all the range of motion of the exercise.