Garage doors come in a variety of dimensions, but 9 feet by 7 feet is a common size. Garage doors are composed of multiple panels joined together; each panel is narrow enough so that the the wheels on either side of it can navigate the 90 degree curve in the door track. If a panel warps or suffers impact damage, you’ll likely have to replace it rather than repair it. It is usually cheaper to replace an individual panel than it is to replace an entire door. Replacing the panels on a 9-by-7-foot garage door requires a few basic tools.
Loosen any bolts holding the panel in place on the door, using a wrench or screwdriver. Each panel is held in place by a hinge, so pull the panel off the hinge once the bolts are loose. The panel slides off the track on some models, meaning you'll possibly need to pull off lower panels to get to the ones you want off the door.
Open and close the door several times to make sure it operates correctly and the panels aren't getting stuck.