You don't say, but I guess your tank has not been cycled.
This page has many useful links on cycling as well as some other aquarium basics http://www.aquariumadvice.com/forums...d.php?t=154837
For example, your tank is not really suitable for goldfish. They get big and are really messy fish, part of the reason for the high ammonia.
You need to do some water changes to lower the ammonia and then cycle the tank as explained in the link
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