Your camper has two different power systems, a 12V DC one that is permanently installed and a 120V AC one that you need to provide the power for. To get the camper outlets to provide 120V AC electricity, you need to plug the camper into a source of 120V AC electricity via the shore power cord. This source can be from the electric grid or from a generator. Alternatively, you can install an inverter which will provide 120V AC electricity from the camper's 12V DC battery system.
Some good reading material:
The 12volt Side of Life (Part 1)
__________________