Unplug the washer. Remove the back panel and locate the pump--the hoses will run to it. Disconnet any hoses and belts attached. Remove and install new pump and reconnect hoses.
I am all thumbs when it comes to repairs or replacements. My motto is "when I cannot do it, the repairperson can." I would automatically speed dial my local plumber to replace a water pump.
You must remove the old pump first. Then take the new pump and connect the pipes together, making sure they are secure. It is not recommended to do this on your own.