Walls are constructed out of pieces of 2-by-4 lumber called studs. If you attach the stair rail brackets to the studs, the stair rail brackets will attach the oak stair rail sturdily for years to come. Locate the studs in the wall along the stairwell with an electronic stud finder using the method recommended on the stud finder packaging. Mark their positions with a pencil.
Buy one handrail bracket (exactly as pictured in the image above) for every 4 feet of stair rail that will be used. You may not use this many, but it will be good to have one or two more stair rail brackets on hand just in case you need them.
Measure up from the stairs 30 to 36 inches, or the most comfortable height for your family, and make a mark where the studs are located. Attach the stair rail brackets to the studs that the ends of the length of stair rail will reach, either with the screws provided with the stair rail bracket or with longer drywall or wood screws.
Using a helper, hold the stair rail up to the brackets so the retaining bracket can be attached to the oak stair rail over the stair rail bracket. Drive the screws through the holes in the brackets into the stair rail. When the stair rail is supported by the two end brackets, begin fastening the rest of the stair rail brackets evenly through the middle of the oak stair rail.