This posture stretches the front of the thighs and helps to open the chest.
Start by sitting on your heels (vajrasana), then lift the sitting bones a little and bring the shins to the outside of the legs next to the hips. Keep the knees hip width apart to avoid any strain on the knee joints. If the buttocks do not touch the floor comfortably, sit on a block or cushion to avoid strain the body too soon. In this case also place a support under the lower back.
Exhale and gradually bring the torso down to the floor, using the hands for support, then stretch the arms out over the head. Relax the back and shoulders, bringing the lower back down. Breathe normally and hold the position for about 30 seconds.
To come out bring the arms forwards and sit up straight, using the arms for support. You can then lean forward and rest on the child pose to counterbalance this pose.