Place a rope attachment at the top of the cable machine and grab onto it with both hands using a neutral palms-facing-in grip.
Take a small step back and stand with your waist very slightly bent forward with both feet side-by-side or one in front of the other (choose whichever feels most comfortable).
With your elbows tucked in towards your sides, press the rope down while at the same time forcefully spreading the rope apart. Continue until your elbows are locked out and your triceps are fully contracted.
Pause briefly and then raise the rope back up until you feel a good stretch in your triceps, and repeat.