I need to work on the door lock of a 2002 Explorer, how do I remove the door panel?

Roll down the window and then remove the window handle (if not electric windows) by taking a thin object and pushing the locking ring off the slot behind the handle (if you push in on the door panel right by the handle you should see the ring) and then pull off the handle. Next remove all of the screws usually located at the arm rest and around the door handle. Also some vehicle have a screw or 2 at the bottom of the door panel.

Once all of the screws are removed, take a screw driver and gently push it under the door panel at the bottom about 6" from the outer edge of the door and move it to the left until you run into a pin. Take another screw driver and push it under the panel about 4" left of the other one and push it right till you find the other side of the pin and slowly pry with both screw drivers. This will pop the panel off the pin. Next put your hand under the panel and slowly slide it towards the right until you locate another pin and with your hand on one side of it and your screwdriver on the other side pop that off. Continue around the rest of the panel popping it off the pins one at a time. Do this across the bottom and up both sides. Be very careful not to pull it more then 6 inches away from the door at a time.

Once you have popped the panel off all of the pins, pull it out from the bottom and look underneath it to locate and unplug any wire harnesses for electric windows, electric locks, remote mirror/etc. Once it is free pull out on the bottom so that the panel is about 12" away and push up on the panel. There are clips at the top and this will slide them off. That is all there is too it.

I am replacing my mirror on the right side of my truck
I need to know how to take the panel off with out breaking it and I have power windows

The instructions above applies to your panel as well. I wrote it to cover both panels regardless if you have electric windows/locks or not. The only difference between the 2 is if you have electrics you need to pull the panel out about 12" after you have popped all the pins and unhook the wire connectors for your eletrical options...