This is how to backside shuvit.
1. Have your back foot on the tail, but more on the toe side, where the concave meets the tail. Place your front foot in the middle or on the front bolts. Your front foot doesn't do much in this trick.
2. Bend your knees a little. Not too much, just enough to jump.
3. At this point, unbend your knees and jump. AT THE SAME TIME scoop your back foot back, toward the heel side. This should cause the board to spin.
4. Watch the board complete a 180 spin.
5. Catch the board with both feet on the trucks and roll away.
That is how you do a backside shuvit.