Adjust the height of the chest padding so that the top of the pad is at your mid chest region when holding the grips. Place your foot against the platform.
Starting with your knee bent, kick your leg back and up in an arc until your glute feel 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.