This story covers installing nail-down engineered flooring.
Roll out the underlayment and staple to the subfloor. Starting on the longest outside wall (usually the straightest), measure from each end of the wall the width of one plank (including the tongue) plus the expansion gap. Snap a chalkline between marks to serve as a guideline.
Stagger joints in subsequent rows by 6 inches. Use the pneumatic nailer to drive nails through tongues; use a tapping block and a hammer to snug together tongues and grooves, edge to edge and end to end. Be sure to leave the suggested gap between the ends of the rows and the wall.