First, determine if they are disc or drum. If drum, remove the drum and replace the shoes. If they are disc, remove the caliper (and disc if necessary) replace the shoes and reassemble.
This will greatly depend on what kind of brakes you have and which parts you are trying to replace. Do you have disc or drum brakes? If you have disc brakes, do you want to replace the calipers, pads, or rotors? If you have drum brakes, do you want to replace the drum, or the shoes?
A 2000 Jeep Cherokee would have rear drum brakes.
You have to measure the inside diameter of the drum.
Drum brakes are one of the easiest brake jobs to preform, but remember you may have to have your drums professional turned or possible replace them if warped.
Drums
The grand Cherokee does have four wheel disc brakes. The wrangler and Cherokee have rear drum brakes.
Check related links below for drum brakes.
No, the value will not change at all. If you replace drum brakes with drum brakes as you said youwe're doing, it is the same as it is now, so no value change there unless you change something and replace it with something different, then you may have some value change.
Replacing drum brakes requires that you have special equipment and is rather sensitive work. Remember that a mistake here can be devastating, and make sure you're up to the task. If you decide to do the work yourself, you can find step-by-step instructions at http://www.wikihow.com/Replace-Drum-Brakes.
You have to get a special socket at the auto store.
Replace wheel cylinders