Once you get the wheels off:
1. Unscrew the two bolts holding the caliper together. You should need an Allen wrench, and the bolt heads are on the back side of the caliper.
2. Slide caliper off of rotor and hang it with some wire or rope, you don't want it hanging by the brake line.
3. Pop off the dust cap in center of hub. Use a small screwdriver to pop it off.
4. Remove the cotter pin by bending it straight and pulling out with a pair of needlenose pliers.
5. Pull off the little cap, exposing the hub nut.
6. Unscrew the hub nut. Be smooth with it, they aren't too tight.
7. Remove the hub nut and the washer and bearing behind it. If the washer and bearing don't come off, just grab the rotor and pull it off slowly, making sure you catch the washer and bearing.
Voila, it's off! Probably a good time to repack the bearings with some fresh grease.