As bowmore said, if you want a "quick" transfer of power, you will need to have an expensive transfer switch installed. Unless you spend thousands on a Generac, etc., you will still have to start the generator. AND, you do NOT want to run it in the garage, unless you want to risk carbon monoxide poisoning.
I keep mine near one of the garage doors, and when I run it, I push it outdoors. I keep two good extension cords nearby, and hook them up to outlets in the garage which are wired to both sides of the main circuit breaker box. If we lose power, I set up the generator, start it up, string the cords, and turn off the main breaker before I plug the cords in. That gives me 25 or 30 amps which is enough to keep the lights, fridge, and other basics working. I also shut off the breakers to the hot water heater, furnace, and AC....since if those tried to kick in there would be a substantial drop in voltage that could destroy those expensive appliances. Turning off the main breaker is especially important, because if left on, the generator would try to send electricity to the entire neighborhood....which would result in a huge drop in voltage, and wipe out everything...even a light bulb.
There's a lot to take into consideration when trying to use a generator.
