Locate the sprinkler that you want to change to a pop-up sprinkler.
Dig an area about 1 foot in diameter around the sprinkler head, digging down no more than 6 inches deep.
Grab the exposed sprinkler with your hand, and turn it to the left until it pulls free. The sprinkler is attached to a plastic riser below the unit.
Wrap the exposed ends of the sprinkler riser with a single layer of Teflon tape. The tape lubricates the pipe threads and ensures a watertight connection.
Place the pop-up sprinkler head on the riser, and turn it to the right until tight.
Replace the dirt around the base of the new sprinkler, and run the system to check for performance.