Measure the walls in the living room area.
Cut the crown molding to the length of each of the walls.
Trim the ends of each piece of crown molding meeting at an outside corner to a 45-degree angle with a backsaw in a miter box.
Trim flat the end of one of the two pieces of crown molding that meets at an inside corner.
Miter the other piece of crown molding that meets at the inside corner to a 45-degree angle.
Cut the outline of the crown molding along the outside angle of the mitered piece for the inside corner with a coping saw.
Attach the cut crown molding pieces to the walls by nailing 6d nails into the studs at the top and bottom of the crown molding around the living room area.
Fill in the nail holes with wood putty and allow the putty to completely dry.
Paint the living room crown molding to match the decor of the living room.