Car Woes

Well I got back with a few gallons of gas for our 1984 Ford Aerostar Van. However there is a problem. Its obvious where the gas tank is, but its totally flat I don't know how to get in there. I am not a moron either, although a few would beg to differ. I am thinking its automatic, yet I can't find an obvious switch either. It has no manual. Think Ill look on the internet for answers. bye bye.