Well it depends on if it's a 4x4 or a 2x4. if it's 4 wheel drive then the rotor pretty much falls off like Curtis said.
2wd is another barrel of snakes. you gotta take the caliper off like above, but the rotor is part of the hub, and you have to first take the dust cap off with a hammer and screwdriver, then dig around in the grease for the cotter pin, remove it, then take the lock off and then the big nut, pair of pliers will take that out it's usually not much more than finger tight. Now the rotor slids off the spindle. while you got it out and it's a 2wd might as well repack the bearings using bearing grease and get a new grease seals.