Find the "Drop Spreader" settings on the instructions for the lawn sulfur. These are typically located on the back of the package, and will instruct you to adjust your spreader to a certain number.
Adjust the dial on your drop spreader to match the number as instructed on the distribution settings of the sulfur. This ensures that the sulfur is spread properly to avoid raising the soil acidity too rapidly.
Pour half the bag of sulfur into the drop spreader, and move the spreader to one corner of your lawn. When the spreader runs out of sulfur, pour in the other half. Using half the bag at a time makes it easier to operate the spreader.
Engage the spreader so it releases the sulfur, and immediately begin walking around the perimeter of your lawn. Keep a steady walking pace for the most even distribution.
Disengage the spreader once you have returned to your starting point.
Move the spreader to one end of the lawn, and set it up parallel to your first pass. Engage the spreader, and make a straight pass across to the other side of the lawn.
Disengage the spreader as you turn it around, then engage it again and make a pass adjacent to your first in the opposite direction. Continue spreading the sulfur in adjacent passes until you have covered the lawn.