I have to change the water pump how do I get started

The only sensible way to answer that question , is to suggest you have a shop do the job. IF done improperly , it may cost you the engine!! Try youtube for some basic info-videos . It is listed as a chain-driven water pump and that engine has one primary and two secondary chains. This is probably not the most do-it-yourself friendly engine to try your luck on. Also , buy a service manual BEFORE you start , that will maybe prepare you at least a little better and be sure you have all the needed tools.