One thing some people in a units of your vintage have also experienced, with the propane is the addition of a safety feature to stop the free flow of propane, in case of an accidental hose break. First thing like everyone else has said check for propane at your stove. Light the stove and let it burn for a few seconds or longer, this will confirm you have gas flow. This will also get the majority of air bubbles out of the line if there are any. Then light the furnace.
If you do not have gas at the burner, then check your tank to ensure you have an open valve and that you have gas in the tank. If the valve is open and you are sure there is propane, close the valve at the tank. Unscrew the hose from the tank and open the gas valve at the stove to release any pressure in the line. This should reset the free flow valve. Then connect everything thing back up. SLOWLY and that is key, open the propane valve at the tank. Then go light the stove to purge the air. Then try the furnace, it might take a couple cycles to light, as there maybe some remaining air in the branch line to the furnace.