How to replace the oil filter housing?

I noticed that the car was starting to leave puddles of oil in the driveway, so I got a diagnostic and was told the valve cover gasket, and possibly oil drain plug were the causes of the leak. After replacing the valve cover, the car is still leaking as now they believe the cause is the oil filter housing. Can you please tell me how I can replace this myself because I feel like I’m being ripped off? Thank you!