Step up and grasp bar with underhand shoulder width grip. Kneel onto platform or step onto bar.
Pull body up until elbows are to sides. Lower body until arms and shoulders are fully extended. Repeat.
See suggested mount and dismount. Some assisted machines require you to stand on platform or bar. If no assisted machine is used, assist as needed by allowing training partner to pull feet up behind legs or push self up with legs on elevation. Also see self-assisted technique without machine.