If the metal hinges on your paneled garage door are squeaky or broken, you pretty much have to replace them. It's much safer to simply install new ones than to try to go on with some spit and duct tape.
Before you can take out the broken hinge, however, you have to lock your garage door into the open position, to be certain that it won't fall on you. That would hurt a lot, not to mention be a pain to re-rig up. Be sure to also shut down and unplug the automatic garage door opener while you are working on the hinges.
Removing the hinges themselves is not terribly difficult, it's only making sure you don't lose control of the panel once it's loosened. First, unscrew the nuts from the bolt on the hinge. Then, take a hammer to the hinge bolt, tapping it until it releases. Don't forget to leave the nut on the end of the bolt once it's unscrewed, otherwise it'll have no protection while you're tapping it out.
Once you've removed the hinges, grab your new ones and put them in place. Tap the new hinge bolts through the holes left by the old ones, from the outside if possible. That's the best angle. Once it's in place, you can then tighten the nut.
Then presto! You've fixed your garage door hinges.