You need to place a bench behind the Smith machine. The bar should be to a height of approximately 1 meter. Lie down under the bar and place your feet on the bench. Your chest shloud be under the bar. Grab the bar using a prone grip wider than shoulder width apart. Raise your hips and contract your pelvic floor and core while keep your body straight.
Pull the bar towards your torso until your hands are next to your ribs while you exhale. Return to the starting position with a smooth movement while you inhale. Make sure your shoulder blades are always retracted.TIPS: The exercise key is quality over quantity. The trick is to perform the exercise using proper form. Alter your grip (neutral, pronated, supinated..) from time to time to train the muscles from multiple angles.