Things You'll Need
Socket set and socket wrench
One damaged panel on your garage door doesn't mean you need to replace the entire door. Replacing just the panel will save you time and money, since a single replacement panel is not nearly as expensive as a completely new garage door -- and it's an easier job to fix a panel than it is to remove an old door and replace it. Even if you have no experience in working with garage doors, you can tackle this job in an afternoon.
Raise the door. If it's connected to an electric opener, unplug the opener. Stand on a ladder and unhook the springs on either side of the door. Carefully lower the door -- it will be heavy, so be prepared.
Unbolt the track rollers from either side of the panel with a socket wrench. Remove the rollers. Unbolt the hinges attaching the panel to the panel above or below.
Lift the panel you're replacing out of the door. Slide the new panel into position and line up the track rollers and hinges with the predrilled holes in the panel. Bolt these into position with the hardware you removed earlier and your socket wrench.
Lift the garage door back to the upright position, and reattach the side springs into position. If you have an electric opener, plug it back in.
Garage door panels are not universal. Get a replacement panel from the manufacturer of your original garage door.