Reach with the back hand behind you as you go over to touch with that first, almost like lowering yourself to the ground. One version of that is called "falling leaf" if that gives you a better idea. Important part is to tuck your head. Start with shite holding on all the way through the throw at first, work up to shite releasing you.
Oh, and DON'T let your legs slap together. "Things" will get "caught"...you'll regret it!
Keep one leg straight and the other bent. Generally the side that you slap with is straight, the other bent, the shock absorbed on the ball of the foot of the bent leg.