
Its not your fault, very very few people know, and those who SHOULD ie those in the industry, either dont, or dont say anything.
Honestly, despite the cold weather, id introduce the fish to the pond now unless they really are tiny little things. Put them in individual fish bags (go to pet shop that does fish and ask for some/offer to pay for some), then you float the bag in the pond for an hour or so, letting a little of the pond water into the bag every fifteen minutes, when bag and pond are same temperature, gently let the fish go.
They may be too small to survive a winter in a pond, hard to say, but then the effects of ammonia and nitrate burns may finish them off also.
Goldfish ARE very hardy, and sadly that is why they carry on being kept in improper conditions, couple that with the fact that many people think 4/5 years is an excellent age as they dont know a goldfish should make 20 years old, and you can see why it happens over and over again.
If you do want to keep fish, get a heater in there and a decent filter. Set it up from scratch, let it run, testing the water every day to see how its doing, for around 3 - 6 weeks. Then you could probably keep a school of small tetra types (there are the obvious neons, cardinals etc, adn the less flashy/garish glowlights, lemons, x-rays) and a few corydoras who will scavenge off the bottom (they do also need feeding with appropriate bottom feeder food).
Tropicals produce much less waste, and the tetra types i ahve mentioned grow to a max of two inches (one for the glowlights and neons), the corydoras, the commoner ones (bronze, peppered, albino) will not make more than 3 inches.
You can do a lot with a small tank, especially if you go in for planted tanks like i do, with lots of plants and just a few fish to show it all off. But, they ARE much harder to manage than a big tank - anything goes wrong and it goes wrong FAST because there isnt much water.
That said, my 12g tank has been stable for months and ive done hardly anything to it, I know the water quality MUST be fine because i have a bamboo shrimp in there and they are incredibly sensitive to poor water quality.
Heres my two footer (12g)
http://i27.photobucket.com/albums/c164/FishyFishy123/KitchenTank12.jpgHeres what you can do with four foot...
http://i27.photobucket.com/albums/c164/FishyFishy123/fourfooter.jpgEm