Take an underhand grip on the machine handles such that your palms face backward. Now lock your thighs under the knee support to prevent you from lifting your butt off the seat. Angle your torso back just slightly and keep your chest popped out, not collapsed. Feet should be flat on the floor and your arms now extended. This is the starting position.
Commence the movement by pulling the bar down and squeezing your shoulder blades together. As you move the elbows down and back, keep them close to your body while you exhale and push your chest through the movement. This will naturally create a reverse curvature in the lower back and will engage the target muscles of the lats. Do not swing backward or try to use momentum to pull the bar.
When you have reached maximum range of motion at the bottom, squeeze for a second and then reverse the movement by extending the arms to the starting position, inhaling as you do.