The back to wrapped is a great progression trick to learn when you have your backroll to toeside under control. Once you learn the Back to Wrapped, you can start to learn a Back Mobe, essentially the same trick, but passing the bar in the air.
To land your first back to wrapped, ride into the trick and unhook. Pop as though you were going to land a backroll to toeside, throwing your head over your front shoulder and planting your back foot on takeoff. As you come around the backroll pull your arms in close your body and rotate as if you were going to toeside but pull the bar in towards your back hip. From here you should be spotting your landing for you landing heelside.
Release your front hand from the bar and and look over your back shoulder. Your weight should be entered over the board as you land. Bend your knees on landing and pass the bar, you've just nailed a Back to Blind!
unhook and go into it as though you are going to throw a big back-to-toeside, keeping your elbows bent
Once you've got to the 540 (back to toe) rotation, continue to spin by looking over your front shoulder whilst pulling hard on the bar. The higher you get your your legs, the easier the rest of the rotation is (thanks gravity).
As soon as you've given the bar a good pull into your back hip, let go of your front hand whilst continuing to look over your front shoulder
spot your landing and let your legs follow you around. You'll need to let your arm go around your back, bending over to allow for your arm to be kept straight if need be (try to keep the bar as close as possible though!)
land downwind with your weight over the board, pass the bar once youve landed. You've just nailed a back to wrapped! Sick! PKRA here you come.