Start by removing all of the components that are in the way of removing the pump. Then you pull the pump off and replace it with a new or rebuilt unit. Be sure to put the gasket on correctly and use gasket sealer to make sure it seals well. Then the rest of the installation is the opposite of removal.
Disconnect the battery. Tale off the serpentine belt. Next remove the bolts for the water pump and detach any hoses connected. Drain fluids and catch securely. If fluid is in good condition, you can use it after pump is replaced. Then unbolt the water pump. Install is the reverse.