Answer:
Well, here are the basics of taking care of goldfishes: You must have clean, fresh water, when you feed them they have to finish it within 2 min., you need a air pump, you need a filter too, some decorations improve the fish's well-being, your goldfish's temperature should never rise above 74° Fahrenheit (about 23.5° Celsius)( a thermometer would be good), must have a 10 gallon tank not fishbowl, and even when they still look hungry don't feed them anymore they just always want more(fee twice a day)if you do you might overfeed them.
If this is not enough information, here's a helpful website about goldfish care: http://www.firsttankguide.net/goldfish.php