I can tell you this. You see that small copper tube coming out of the control unit (the thingy with the On Off Pilot),,,,,,,,,well thats the Thermocouple tube and the pilot is located at the end of that tube inside the firebox where the Thermocouple is. Its (thermocouple) right above the pilot because the pilots flame and heat is what keeps it turned on. Soooooooo see where that little copper tube ends because right inside there is the thermocouple and thats where the pilot will be located just below. Some furnaces have a sight glass and top screw you can loosen to turn the glass and get in there to light the pilot. The gas has to be on and the On Off Pilot turned to PILOT and held down or depressed or turned against spring pressure AND HELD THERE as you light the pilot and then continue to hold it down or in the spring position for 15 seconds or so until the thermocouple heats up enough to keep the gas on. A weak thermocouple may fail to keep the gas on as it should i.e. it would turn off after you released it from the PILOT position. Some furnaces have a piezo push button that snaps when depressed and it creates a spark there at the pilot so theres no matches etc used and they may NOT have a window you can ever open to gain access MAYBE YOU HAVE A MANUALLY OPERATED ELECTRIC PIEZO IGNITER??? if so look for a little red button you push and it snaps.
PS I bet you can go online and download the manual and it will tell you what you have (piezo or match light) n how n where to light it
Ol John T in Indiana
Note: John posted this as a response and I thought it was soooo good that I added it to our RV Repair forum. Thank you John T! pat