If you can afford it, call a mobile RV repair guy in your area or take the rig to a repair place. It sounds as if there is no 12 volt house battery power to your furnace(heater). It could be something as simple as a poor ground connection.The blower should at least run if the furnace is getting power.Make sure that your auxiliary battery switch is in the right position for 12 volt items to get power. Chances are you won't be able to fix a plumbing problem on your own either. It would be good if you can find an honest local repair service that you can contact for advice with problems or service as needed. Don't let people take advantage of your position, get a second opinion and estimates if they want to do major repairs/replacements. You need to buy a good "how to" book on RV use and maintenance and learn to check and maintain your house and starting batteries, etc., etc.