Adjust the height of the chest padding so that the top of the pad is at your mid chest region when holding the grips. Then place your foot against the middle of the platform.
Starting with your knee bent, kick your leg back until your glute feels fully contracted. Then slowly lower it back down the same path to just before the start position. Keep your core activated and back straight throughout. Repeat for the desired amount of repetitions then switch legs.
Avoid the use of excessive momentum, keep the movement smooth and controlled throughout.