In this video

Carefully lay the prepared tread into place. Push it back firmly against the riser and tap it down to ensure a tight fit. Once satisfied with the fit, use a nail gun to drive nails across the front edge of the tread, securing it to the stringer. Optionally, for the final tread, you can use a pry bar to pull the skirtboard out slightly, allowing the tread to slide in with a 2-degree bevel and then bond with adhesive to eliminate gaps.