1993 BMW 525 Fuel tank. Not sure if I picked the correct

Engine Mechanical problem
1993 BMW 525 6 cyl Automatic 175000 miles

I just bought this car through a private sale, the tank was on empty. I've got a flat and battery died so I put some gas in the tank today with one of those red containors and right when I put it in, the gas fell out right in front of the rear tire. After the gas dried I looked up under there and saw this little rubber wire with a little bit of a larger head just hanging there. It was dry at that point so I couldn't really tell if the gas came from there. That thing is supposed to be conected to something, I hope it's for the gas, if it is where do I connect it to?