A little bit more detailed information on what isn't working or what you think is messed up would be helpful.
As a basic start, understand that the RV basically has two separate electrical systems: the 120V AC system, and the 12V DC system. The 120V system powers the 120V outlets and whatever is plugged into them, the air conditioner, the microwave, the electric water heater, the fridge heating element when in electric mode (assuming you have an absorption fridge), and maybe a couple other things--though not every device listed would necessarily exist in every RV. The 12V system, on the other hand, powers the lights, the water pump, the controls for the fridge (in both propane and electric mode), the gas water heater controls, the exhaust fans, slideouts and electric steps, and most everything else electrical.
There is a device called a converter that is, at its heart, not much different from a battery charger; it provides 12V power from 120V power when plugged into shore power or using a generator, and also charges the 12V battery as it does so. There may be an inverter, as well, to convert 12V power into (limited) 120V power, and sometimes the inverter and converter are combined into an inverter/charger. Most simpler and/or older RVs don't have an inverter as standard equipment.
If this is a motorhome, there's a third electrical system for the vehicle stuff--starting the engine, running the headlights, that sort of thing. There's some sort of a scheme by which the vehicle electrical system can charge the (house) 12V system when the engine is running.
As part of the 12V system, there's usually a shut-off or battery disconnect switch. In general you would want to leave that in the "on" or connected state. For longer-term storage, it's usually better to physically disconnect the battery if you have no way of keeping it charged than to rely on the disconnect switch that quite often does not disconnect quite everything.
Hope that overview helps some. As I said above, feel free to post with specific problems or difficulties and there are plenty of people here who can help.