First turn off the water going to the faucet. This is in the house. Next take a wrench and turn the faucet off from the pipe, then put a new faucet on, go into the house and turn the water back on. If it leaks, start all over again and be sure there is a washer in the faucet.
You must first locate the water shut off valve to ensure that the water source to your exterior faucet is shut off completely. You may then proceed to begin dismantling the faucet with a pipe wrench by turning the pipe wrench clockwise rather than counter clockwise as water faucets are installed this way.