the seal is actually in the hub(thing rotor fits on) anyway you need to unbolt the axle and pull it out, unbolt the caliper bracket, remove the rotor. to get the hub off remove the retaining ring with a pick for screwdriver, slide out the lock, mark the groove the lock was in. remove the bearing retainer with either the special socket or a chisel and hammer. the hub should slide off the axle tube now. remove the seal with some kind of prying tool and install the new seal, put a little grease or gear oil in the new seal before putting it back together. you'll want to clean all the old oil up before putting everything back together a few cans of brake cleaner and shop towels will help out. you should replace the park brake shoes and maybe brake pads too since they are oil contaminated, a big pair of pliers or c-clamp will be needed to push the caliper pistons back in if you put on new pads. it's also a good idea to but some thread locker on the caliper bolts so they don't fall out. you will also need a new axleshaft flange gasket or you can use a little silicone. i know this sounds like a big job but it's not too bad if you have some experience as a backyard mechanic. have fun!!