my gas gage is not reading correctly the proper fuel measurement. how or where can i go to test my gas gage?

By law, vehicles must get about 300 miles to a tank of fuel. I cannot see a Town n Country going that far on 8 gallons, so your float is stuck or the rheostat is shot. Ethanol fuels attract water that destroy all sorts of metal and rubber/plastic parts, so it's not so odd to have a failure like this. Unfortunately, MOST fuel injected vehicles have both the pump and the sending unit as an assembly inside the tank and since it's not reading correctly, no further testing is necessary. It very likely needs replacment. This is not a do it yourself job. It deals with gasoline ...... and it might be a lot of HEAVY gasoline since you don't really know how much you have in the tank. It's a clumsy, dangerous, heavy job with lots of diry, things dropping into your eyes, ears, nose and mouth and an unstable, sloshing, balancing act that is even tough on a professional level.