Get a book, it will make thing easier.. Even a haynes is ok.. If you can't get one, check out the repair info pages on autozone.com...
But.. in a nutshell..
Take off the tires
Take off the calipers
Take off the outer retaining nuts (if you still have the auto hubs you have to pull the key from the keyway, then take the big nut off.. I "think" its 2 3/8" but I'm not positive on the size)..
Now take off the out bearing..
I use the following trick to take off the inner bearing/seal
Put the outer nut back on.. now grab the rotor and yank it towards you. You have to pull hard/sharp. What should happen (sometimes takes a few pulls) is that the bearing/seal will come out of the back of the rotor when it hits the outter nut.
now take the outer nut back off
If you not putting in new races (I used to not do that since I would end up replacing my rotors before the races needed to be replaced) you just grease up the bearings, put the inner bearing in, install the seal, and then reasseble in reverse order..
You want the book for the torque specs.. IF my memory is correct, its 35ft lbs for the outter nut, then turn back 1/2 turn, then tighten to 18 inch pounds.. but look at a book to be sure..
Its not that hard to do.. If I already greased the bearings it take me longer to jack up the truck, put it on jack stands and take off the tires than it does to actually change the bearings..
~Mark