First you jack your car up and for safety you place it on a floor jack . Then you remove the brake drum off . Once you remove the brake drum you turn your the bearing until the hole lines up with the four bolts that hold it .
Once you remove the bolts then you can remove the bearing , You might need a rubber hammer to tap it off . Then you get brake cleaner and spray the area to clean it up . Remove any grease there . While you you are there check out your wheel cylinders for leakage and your brake shoes for any wear . Give them a lightly sanding if they look shinny .
Compare the two hub bearing . The OEM has a open back and the aftermarket has a sealed back . .
Then you can put your hub bearing back on put some anti seize on the bolts then tighten and recheck . Spin it . Put some anti seize on the studs . Put your brake drum back on and adjust your rear brakes if necessary .