Remove Old Spout
If for some reason your old spout becomes damaged you will need to replace it. Look for a retaining screw on the bottom of the spout. If you see on, use a screwdriver to remove it and slide the spout off of the pipe.
If you do not see a retaining screw, use an adjustable wrench wrapped in tape to unscrew the spout from the pipe. Be careful not to apply to much pressure and damage the pipe our sprout nipple.
Install New Spout
Put joint compount on the nipple treads before installing the new spout. Put the new spout back on the pipe, either by sliding it on and replacing the retaining screw or screwing the spout back on by hand.
Complete the job by using silicon caulk around the edge of the spout.