STARTING POSITION:
Select the appropriate resistance in the weight stack. Stand up straight facing the pulley and spread your feet at shoulder width apart. There should be a handle that is attached to the lowest level of a pulley. Grab it with your right hand using a prone grip.
MOVEMENT:
Retracting the shoulder blade, pull the handle to the side of your chest while you exhale. While your are doing the exercise, move only the arm, 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.