You enter the pose in garbasana /or garba pindasana -- the embryo pose with legs locked in lotus, and arms through your legs. Then roll over in a rocking motion. The last few rolls should bring you up on the mat, till you lift your hips clear off the mat and hold. Once you go up, your calves and things should lift "grasp" the arms, to lift you even higher.
Just now, the image above was not entered that way. But will post one soon, with a higher lift, to explain it in detail.