Please remind me how to start the furnace (seriously).

Light the stove first if you have not used any propane in a while. This will help assure the lines actually have gas in them. Then if yours is like most, turn the thermostat to heat, and then slide temp control to a high number. You should soon hear the fan come on followed by a clicking at the furnace as it tries to light the gas. You should be able to hear it light. Sine you have not run it in a while, you may smell some dust burning off but should go away shortly.