Here is a great section to learn more about keeping GF...
Freshwater & Brackish - Coldwater, Native Fish & Ponds - Aquarium Advice - Aquarium Forum Community
and why he needs a bigger tank...29G Long would be the next or 40G breeder tank
Which kind of GF do you have, a Comet?
You need Prime water conditioner and get the little bit bigger bottle if you can because with a GF and a fish in cycle you will need it and get a pack of eye droppers so you can use the correct amount of it, otherwise one tends to use much more than necessary.
And here is some info about the "fish in" cycle...
Fish-in Cycling: Step over into the dark side - Aquarium Advice
That ought to get you started!!!
In my signature below are some additional things about learning how to keep fish...