Yep, you are definetly in for some work if you started with goldfish. Most people don't realize how big goldfish get (or that they can live for decades if properly kept). Read the sticky thread on Cycling and get a testing kit (liquid tests, not the crappy strips). Ammona and Nitrites should be at zero, nitrates no more than 40ppm, but less than say, 5 ppm, means the tank is uncycled.