Hi Mossrisjhons,
The best thing to do might be to have as large a tank (aquarium) as you can get. The goldfish need oxygen to breathe, so don't keep too many, maybe 1 fish per each 10 gallons would be okay. I don't think you can keep many aquatic plants in a goldfish tank, as the goldfish will eat them. It will keep the fish healthy, though. Don't overfeed your fish, as the uneaten food will cause the water to go bad. Just a little bit of food once or twice a day should be fine, be sure that they eat everything and don't leave anything behind.
Yes, it would be a good idea to boil the rocks and driftwood first, that will eliminate any parasites or harmful organisms that are on them. I raised tropical-fish and goldfish myself for many years, and I enjoyed it. I had a few goldfish that I'd had for 14 years, they grew quite large, I had them in a 50-gallon tank in my basement. I had to give them up when I sold my house, and I miss them. Good luck with your fish-keeping, and have fun.
Edited by Windemere - 15-Aug-2009 at 08:18