Welcome to the forum. You will often find that any question you have may have been asked/answered several times by others - using the forum search feature located above/left will usually provide answers to most of your questions.
Concerning your furnace. Make sure your thermostat is set to the proper position (heat on) and that your propane tank has gas and is turned on (tank has valve). Some rigs have propane alarms that have to be turned on in order for gas to flow.
As others have stated -check your furnace fuse and lighting the stove top burners will purge the system of air. Low coach battery will also prevent a furnace from operating - any tire/auto house will load test your batteries for free - something you should do anyway since your rig is used and having good batteries is a big deal especially in winter.
Good luck