Work out where you want your sprinklers to go, making sure the arc for each one overlaps the area of lawn they're covering. Dig a trench around the perimeter of the lawn and calculate how many sprinklers you will need.
When everything is in place, flush the system to get rid of any dirt. Attach the small risers to each pop up sprinkler unit and screw them into the joins.
Now, using your spade, backfill the trench with soil to cover up the whole watering system.