Sweep the stair off thoroughly using a broom to remove all sand and grit from the surface of it.
Measure the width of one of the treads using a tape measure. Divide the width measurement in half to arrive at the center point of the stair.
Locate the center point of the stair with the tape measure and mark it with a pencil. Repeat the process for each additional stair tread to mark the center of each one.
Place a single stair pad over the center pencil mark on a stair and move it forward or back until there is an equal amount of stair space behind it and in front of it.
Fill a staple gun with 1/2-inch stainless steel staples. Insert a staple through the stair pad at each corner and in the center to secure it to the underlying step.
Set the staple gun aside and tap the top of each staple once or twice with a hammer to sink it flush with the stair and to ensure it is securely in the wood.
Repeat the process to install additional stair pads on all remaining stairs.