This is an easy job... but a time consuming one.
Take both tires and hubs off. Then loosen both axle locknuts towards the left. Pop the masterlink off the chain and then take chain off sprocket.
Then the sprocket hub slides off to the left. Brake caliper on the back comes off the disc. Take it off and let it on the swinger or just let it hang.
Then tap the axle out towards the right if looking from the rear. Then take the carrier off to put new bearings in.
Note: If you never took the axle out, it might be hard to come out. Get a piece of woods, put it against the left rear axle end and give it a good whack with a buddy holding the bike.
New bearing are always good to have in there. Also, try and grease them as much as possible, and if you really want it to be easy, install a grease zirk on that carrier. That will make life alot easier for you greasing it.
But definately replace those bearings. Use the above methods, they all work.
Good luck