to the forum and congratulation on your "new to you" Laredo.
The switch you're talking about is most likely for the hot water heater. The furnace is operated by the thermostat, there is no "off/on" switch for it. Be careful that you don't turn on the electric side of the hot water heater unless it's full of water as the electric element will burn out in just a few seconds unless it's submerged in water.
Look around the forum, there's a search feature located in the top blue bar on every forum page, if you can't find what you're looking for, try a search, if that fails, start a thread and ask for help. Someone will direct you to the right place to get your answers if it's more complex than just a few lines.
Enjoy your visits with us, we're happy to have you as a new member. Enjoy your Laredo !!!!!