Look in the access panel to you water heater on the outside of the camper. Usually there is a small rocker switch that says "on & off". Switch to on and you should be all set. Sometimes the switch will have a small cotter pin in it to stop you from accidentely turning it on, make sure this is removed. The switch on my Surveyor was hard to see. Hopefully yours is the same.
I wish the best for you and your family and hope your husband returns home safe. Please tell him THANK YOU!