How do i safely shut gas off and use flea foggers?

We have flea infestation and have unsucessfully tried the sprays and powders in the house as well as keeping First Shield trio on my dog. Now it is time to try foggers. I know we need to shut off anything that uses gas. That means hot water heater and stove. Our furnaces/air conditioners, we have one in the attic and one outside, are also gas. Do we need to shut them off as well. Do we shut the main valve off outside to the gas and then have to re-light all the pilot lights on everything. My husband says he is not sure how to relight the furnaces/air conditioners and does not feel good about doing this. But we have tried everything else. Can someone tell us how to do this?