First, you need to stand in front of the player at the double block while you do this call for the ball, you want to catch the ball and keep looking at your defender, the other side of the key, and outside. Then you need to keep your back to the defender and start backing them down while dribbling the ball, From there you can do a variety of moves to get a shot off like the drop step is where you take a big pivot around your defender and seel them off and get an open shot and many more.  Watch this video for more post moves