http://www.aquariumadvice.com/forum...ou-get-started-with-your-aquarium-154837.html
I suggest reading through a few of these articles about getting started. They are pretty helpful! Pet stores are notorious for telling people the wrong info about cycling.
Since you have fish, you will want to do a fish-in cycle. It can easily be done without hurting the fish. You already have a test kit so you are in good shape. The article explaining how to do it is in that link.
Without seeing the fish, it is hard to diagnose the behavior exactly. but,m a few options include not enough hiding places, getting adjusted to the new tank, establishing a social order between the fish, or ammonia agitation to name a few. Keep on top of testing the water and make sure there is plenty of decor in there for them to feel comfortable.
Bets of luck, feel free to ask any questions.