Adjust the height of the platform so that your hips are aligned with the pivot point of the machine. Adjust the padding to be on the outside of your active leg's knee is aligned with your other knee.
Start with your foot pointing upwards by bringing your leg outwards to about 45 degrees or as far as comfortable, then slowly retract back to the starting position. Keep your leg in a consistent position as you sweep it across. To keep stable, tense both your core and the stationary leg. Repeat for the desired amount of repetitions then switch sides.
Avoid kicking out and using momentum or allowing the torso to sway.