Probably VERY similar to yours.
1 on the street side you have three places where you can stick a fresh water hose.
- the fresh tank - it's behind a door that you open then take off a gray plastic cap - DON'T just cram your hose in there and fill - there is back pressure from air trying to escape the tank, and you may fill too fast causing the tank to deform and possibly warping your floor! WATCH it fill and make sure the air is exhausting easily.
- the black tank FLUSH - not clearly enough marked, but it's right ABOVE the fresh water intake - it's a cheap black valve with a plastic lid that often pops off. Over fill this one, you'll have sh** coming out the air stack on your roof. The black tank flush should be used only when you're dumping your tanks.
- The fresh water inlet, also on the exterior, also black, but with a cap on a chain and a hand friendly tightening ring to secure your white hose without leaking
On your water heater - it lights automatically IF you turn it on. In my Airstream the control is IN the bathroom next to the bathroom lights - the bathroom lights are the left switch, the water heater switch is in the middle and the ON indicator light is on the right. It is red and will only come on when the tank lights. It normally stays on for 30 seconds or less. If it's on solid, you're out of propane, or need to switch to the second tank. Every now and then it just fails to light, in which case you turn it off, wait a few seconds and turn it on again.
WARNING WARNING WARNING - if your propane tanks are empty and you take them off to have them refilled, you should turn off your water tank, your stove/oven and make sure your refrigerator is on electric - or turned off momentarily. If you have a heat pump or A/C with heat strips, make sure it's not so cold that the furnace might kick on, or momentarily turn off the heating. Install the tanks and open one or both, light a burner long enough to exhaust the air from the lines, then turn on your water heater and other appliances that might use gas. .... if you don't maybe nothing bad will happen, but you and your rig might go BOOM!
Welcome.... there are no stupid questions... there's just being smart enough to know you're a newbie!