Ankles. Front of your lower legs.
Sit on your heals. Slowly start to relax back onto your hands as you lift your legs. A good option is to put a bolster or pillows under your knees, to make it easier to rest.
There´s not one way to do this pose. Feel the target area, and modify the pose until you feel the target area, and can allow your muscles to relax.
Stay around 1-2 minutes. Then slowly ease out of the pose.