There may be a pushbutton switch near the 12 volt receptacle in a TV cabinet or elsewhere. When "on" a green LED should light and the amplified antenna will feed over the air station signal to the TV, When "off" green LED is not lit and you can feed cable TV signal to TV through an outside connector (maybe hidden in the "shore cable" compartment)When green LED is off, you can't receive TV via the antenna.
Don't expect good reception while driving, requires satellite TV antenna, etc. FYI, The inverter itself uses power from your house battery, inverter plus TV may discharge your house battery fairly quickly.
Your house battery charges quickly from the engine's alternator during driving but very slowly from your converter/charger when hooked up to shore power or when running the RV generator. Learn how to check/replenish battery electrolyte and keep battery connections clean for reliable battery power, house and starting batteries. A simple digital multimeter from Harbor Freight is useful in checking voltage and trouble shooting 12 volt DC circuits.
BTW, the engine starting battery is not being charged while you are connected to shore power on most RV's unless a special device is installed to do so. Good to understand what the converter charger does to charge house battery and provide interior lighting, and how the house battery provides power to the electronic controls in the appliances and blower motor in furnace, etc.
There is also a correct procedure for getting 110v RV generator power into the RV and start up and shut down of roof AC.
If you know all of this please disregard!