The play starts in a box set. Both of the perimeter players are on the ball side at the elbow and block. The post players (or worst ballhandlers/shooters) are on the backside block and elbow. Your best shooter should be taking the ball out and your second best shooter should be at the elbow.
DIAGRAM 1: The play starts with the player at the ball side block setting a back screen for the player at the ball side elbow. The player at the elbow runs a cut to the block (just in case he is open for a layup), and then pops out hard to the corner and recieves the pass.
DIAGRAM 2&3: After setting the pick (and as the ball is passed in), the player who set the back screen pops out and recieves a pass from the player in the corner. As the pass is coming to him, the players on the backside are both coming to the block to set a double screen for the inbounder. The inbounder cuts off the double screen out to the three point line and recieves a pass for a possible three.
DIAGRAM 4: If no three is taken, the two players who set the double screen stay there and set another double screen for the player in the opposite corner (who the ball was inintially inbounded to). The player comes off the screen to the corner where the ball is. The player coming off the double to the corner looks for his shot.
DIAGRAM 5: If there is no shot, the 4 man on the block comes up and sets an immediate backscreen for the 1 man who runs the backdoor lob look and seperates out to the backside wing. We are now in our 4 out 1 in look and can run the offense.