Hang from a vertical object with a wide grip and bring your legs up, so that your body is vertical and inverted.
Pull with the top arm push with the bottom arm.
You can get into the position by hooking your feet on the support and walking them up until you are inverted. Attention: if you do that, make sure you have enough strength to go back down.
Risks
You will be inverted and at some distance from the ground; make sure you can safely go back down before attempting.