Position your rings around your head heigh. Grab the rings with both your arms and bend your knees. Lift your feet off the ground. This will be your starting position.
While keeping knees bent lift them up so they almost touch your chest. Don't rush this movement and don't try to use the swing to make it easier. When lifting your knees up you can protract your scapula.
Reverse the movement and move your knees down but don't touch the ground with your feet.