Measure the walls in your room with a measuring tape to determine how much molding you will need to purchase. Add approximately one foot to each wall measurement to account for mistakes during cutting.
Measure the walls again and mark the measurements onto the molding with a measuring tape and a pencil. For each mitered end on the molding, add the width of the molding to the length of the molding.
This will give you the right amount of molding for the cuts you need to make.
Adjust the miter saw so it is set to a 45 degree angle. Place the molding onto the miter saw with the back of the molding face down on the saw table.
Cut the molding at a 45 degree angle. If the molding needs to be connected in the middle of the wall, splice the two connecting ends.
Splice the molding by cutting each of the ends on the molding on a parallel 45 degree angle. Once cut, the ends should slide together easily.
If you are joining two pieces of molding together for a corner, you will need to cut the 45 degree angles in opposite directions.
Nail the molding onto the wall with a nail gun.