Installing a chair rail can bring visual and textural interest to a room. Before beginning, measure the room and decide how high and wide the chair rail will be. At the hardware store, you can choose between wooden types and foam types. Both are fine, but foam is easier to cut (only requiring a utility knife). Both types can be hung by nails or glued (foam works better with glue). Once you have your materials, measure the height of the chair rail, and use a ruler to keep the lines straight. Attach the rail, and if using glue, let dry for 24 hours. Then caulk and touch up any paint as needed.
Read the full article here: How To Install A Chair Rail