Bend your elbows to let your body dip down between the rings, while keeping your legs straight and parallel to the ground.
Then push yourself back to the starting position.
Form tips
At the top, straighten your arms and push your shoulders down ( Shoulder depression ).
Go as deep as your current strength and flexibility allow.
Risks
The weight of the legs forward will require you to open your elbows wider to perform the dip, which puts the shoulders in a less stable position. Progress carefully and don't overdo it to avoid injury.