Sit down on the chest press machine and grab onto the handles with a medium-width grip. Choose a grip width that causes your elbows to form a 90 degree angle when the handles are fully lowered toward your chest. The seat should be positioned at a height that places the handles in line with your mid-chest.
If the machine you're using has a lever, step on it in order to move the handles forward. Next, press the handles forward until your arms are fully extended in front of you and you feel a strong contraction in your pecs.
Lower the handles back toward you until they are directly in line with your chest, and then repeat.