Park the Jayco trailer in the camping area and level the rig. Place the emergency brake on or place chocks under the wheels. Turn the engine off if the Jayco is a motorhome.
Go to the circuit panel -- consult your Jayco user manual for your specific model -- and turn off the main circuit breaker. Go outside and open the electric connection plug.
Ask the campground manager what voltage protocol is available at the site. Flip the Jayco electric switch to either 30 or 50 volts, depending on what is available at the campground.
Plug the external electric source into the Jayco electric receiver. Go inside and flip the main circuit breaker on.
Turn on a light or an electric device to test the connection.