Start with the giver in a headstand position, as if they are about to take off into a cartwheel. It's a good idea for them to do this with their back against a wall for extra support. Their partner then stands in front, with their back facing the giver's body and their feet resting on either side of the giver's head.
The receiving partner bends over so the giver can insert their penis into the vagina, or in the case of the backdoor cartwheel, the anus. This sexual position is seen as especially challenging because it's difficult for someone to balance on their head, particularly maintaining an erection when blood is rushing to their head.
This position also relies on the receiving partner to maintain momentum and keep the penis at an angle which is comfortable for both participants.