it's going to be quite a job. how much of the bolt broke off in the hole?
to break off a bolt being screwed into a hole probably means that it is probably cross threaded and when the tension of the cross threading exceeded the shear strength of the bolt it snapped. So it will be very difficult to remove. You will probably have to drill out the broken bolt. Start with a small drill bit and try to drill down the center of the broken bolt. Keep stepping up in size until you can get an "easyout" extractor in the bolt and try to reverse it out. You might even have to drill it out bigger and bigger and step up the "easyout" extractors until it backs out the bolt. Sometimes even then, sometimes the bolt won't come out. You might have to drill it all the way out and either rethread the hole or drill it out bigger and install a helicoil.