Most all lights in an RV are 12 v, running off the 'house' batteries. You should also have a chassis battery(ies) that run the engine and driving functions. The overhead lights might be controlled by a switch near the door. I suggest you use your shore cord and plug the RV into a power source at your house. Your house outlets are probably 15 amp circuits, the RV is either 30 amp (3 conductor plug) or 50 amp (4 conductor plug) You'll need adaptors to step the power down from the RV plug to the wall outlet. DO NOT plug it in to a dryer plug, they are 220 v and your RV is 120 v only. Adaptors are available at most any Walmart or RV store.
Once plugged in, your on board converter/charger should not only charge the RV batteries but provide 12 v power to the RV.
Don't try to run the air conditioner while on the 15 amp house power, it's too much.
You might want to read this:
The 12volt Side of Life (Part 1)
Here's a link to your wiring diagram:
This link will take you to HR Owner's manuals. I don't see one for 1997, but a 1998 should be close enough.
Holiday Rambler - ownersmanualshr