Performing the exercise: Set the weight on the machine. Sit in the seat and strap into the machine. Grasp the handles (or rest the arms against the pads) and using the abdominal muscles roll the rib cage down toward the hips. Once in a fully crunched position slowly let the weight back up to a slightly stretched position and repeat.
Tips: Light weight to start will help with ensuring proper form and feeling the abdominals work during the exercise.