If your garage door has only minor damage but its getting on in years, you may want to consider a replacement. Older doors are likely to need replacement sooner rather than later.  

Garage doors are made up of panels that have been hinged together. When one panel is damaged, it can be replaced. Replacing just one panel of the door is often less expensive than replacing the entire door. 

Garage door openers are complex mechanisms. You should use a trained garage door repair technician. Specific part are needed for specific openers.

Warranty are given for a certain time frame.
That warranty can help you pay for repairs or replacement if something goes wrong before that time frame has passed. If you attempt to make your own repairs it can void the warranty. 

The biggest reason you shouldn't try to DIY repair your garage door, it can dangerous. Garage doors weigh several hundred pounds, and it can come down with enough force to cause senous injury. Technicians know how to make repairs with these doors carefully. 

The presence of insulation is the biggest difference between insulated versus un-insulated garage doors. Insulated garage doors feature layers of polystyrene or polyurethane. Insolation can decrease climate costs, keep garage dry, and secure.

The average spring life is 7-9 years, assuming 10,000 cycles at 4 cycles a day. 

Call a Professional to avoid additional damage to your door.