Place a bench, box, or another stable object underneath the pull-up bar. Stand on top of the bench, and grip the pull-up bar with both hands. Your hands should be slightly wider than shoulder-width distance apart, and your palms should be facing away from your body.
Jump up off the bench and pull yourself up. If you can, try to get your chin above the bar. This is your starting position.
With control, slowly lower your body down for three counts or until your arms are fully extended. Be sure to keep your core engaged throughout the entire movement.