Your Airstream has two electrical systems.
One system operates on 12 volts. The power comes from a 12V
deep cycle battery mounted in your trailer. The 12v
battery must be fresh and the wiring in good shape for it to work properly.
battery provides 12 V power to the interior lights and the water pump for the fresh water tank. This system is overload protected by small round glass fuses. The fuses are approximately 5/8 inch long with a thin strip of metel inside the glass. The electrial value of the fuse is stamped on the fuse, IE... 20 A.
If the fuse is "blown" the round glass tube will be intact, but the thin metal filiment will be broken and may appear to be "burnt".
Replace the fuse with the same type, "value" of fuse to restore the power.
The second electrical system is for the 110 volt electrical system power. The 110 v system powers the converter, the air conditioner, the refrigerator, and the interior wall / exterior trailer recepticals that look like the ones in your home.
If you had lights for an hour then all the lights went out at once it is most likely a 12v fuse has blown. That is a quick less than one dollar fix.
The meter everyone has been referring to to chek your electrical circuits is an Ohms/Volt/Amperage meter. The meter can check 12v electrical systems and 110V electrical systems.
When properly used, the meter lets you check electrical system to make sure the proper current is present and that there is no short.
If you are not comfortable with checking electrical systems call someone at this site that has said they are willing to help new folks, or call an RV repairman. It may cost should be less than $100.00 and you can ask the repairman what they found and how they found the problem.