i don't think you're bad.
if your ammonia level is .25 you need to do a water change asap. in a 10 gal
i would change out 5 gals. make sure you use a water conditioner in the tap water you add. i think petsmart sells the liquid test kit. if not the kit, they do sell them separately i believe. the white you see on your fish could be ammonia burn. i'm not sure but i know that your fish will be happier after a water change. if you aren't using a filter in you 10 gal
. you should change the water everyday until you get one. about 50% i would think. check some of the different threads on this site. they might have one on gold fish. i think the most important thing now is that water change. test again after you change out the water. ammonia should be 0.