Grab the uphaul line and carefully stand up and assume the Back-to-the-Wind position with your front foot instep against the mast foot and your back foot, shoulder width away, on the centerline of the board.
 

Bend your knees and adjust your hands on the uphaul so your arms and back are straight; and take up the slack on the uphaul line.
 

Push up with legs and lean back a bit to start lifting the rig. (Top Picture).  A large amount of force is not required.  At first, you should lift the sail slowly to let the water drain off the sail. 
 

Once the top of the mast is level with your head,  pull hand over hand on the uphaul until you can place both hands on the mast. (Bottom Picture)
 

The front of the boom is now level with your shoulders.