Hi Betty
I am assuming this is a mercruiser? I need to know for sure to give you a correct answer and parts diagram. Model year would help also.
OK
What you need to do is split the lower from the upper gearcase. You will need to disconnect the two wires on the inside of the boat that go down to the electric shift. Then remove the bolts that hold the lower to the upper. Once you get it off you will find the housing that holds the waterpump. I usually use an electric impact to remove the bolts.
This is obviously this is a overview of the procedure. If you need more detailed instructions just click back on this question.
Here is a link to a parts diagram. click here
Marine Mechanic
marina owner for 20+years, certified Evinrude tech