http://www.youtube.com/watch?v=t7Wm_6x9Qt0
The proper form: Bicep curls. Stand up with your torso upright while holding a cable curl bar that is attached to a low pulley. Grab the cable bar at shoulder width and keep the elbows close to the torso. While holding the upper arms stationary, curl the weights while contracting the biceps as you breathe out. Only the forearms should move. Continue the movement until your biceps are fully contracted and the bar is at shoulder level. Hold the contracted position for a second as you squeeze the muscle. Slowly begin to bring the curl bar back to starting position as you breathe in. Repeat for the recommended amount of repetitions.