First of all you should find out the exact gallonage, because that allows you to determine how many fish you can safely fit in the tank. Secondly decide if you want a heater, which you SHOULD have for all tropical fish (pretty much everything accept gold fish and bettas are considered tropical (and yes I know bettas are tropical, but they do fine in cooler water.)) Cycling the tank with fish is easy, the most common fish used for cycling tend to be comets and zebra/leapord danios because they are small and "hardy" so start with a few let them sit and do their work, make sure you do water changes every week (30%) and wait till the inital ammonia spike is over then add some more, usually its better to work at that until theres quite a few fish in there, they I would say when you think its ready, take those fish out (most stores are happy to get them back) Then you should be safe to add the actual fish you want, you should still not add too many, because you may add more then your water can handle, so if you are unsure, you can go to a trustable aquarium store (usually one that deals with just fish and nothing else) and follow their advice.
