For this pose you might want to pad the floor below your pelvis and ribs with a folded blanket. Lie on your belly with your arms along the sides of your torso, palms up, forehead resting on the floor. Turn your big toes toward each other to inwardly rotate your thighs, and firm your buttocks so your coccyx presses toward your pubis.
Exhale and lift your head, upper torso, arms, and legs away from the floor. You'll be resting on your lower ribs, belly, and front pelvis. Firm your buttocks and reach strongly through your legs, first through the heels to lengthen the back legs, then through the bases of the big toes. Keep the big toes turned toward each other.
Raise your arms parallel to the floor and stretch back actively through your fingertips. Imagine there's a weight pressing down on the backs of the upper arms, and push up toward the ceiling against this resistance. Press your scapulas firmly into your back.
Gaze forward or slightly upward, being careful not to jut your chin forward and crunch the back of your neck. Keep the base of the skull lifted and the back of the neck long.
Stay for 30 seconds to 1 minute, then release with an exhalation. Take a few breaths and repeat 1 or 2 times more if you like.