You need to get a nitrite, ammonia and nitrate test kit at the minimum.
If the nitrite and ammonia test zero your tank has cycled.
Adding fish:
We all get excited at the idea of adding livestock in our tanks.
To be safe and avoid problems only add one fish per month.
Check about the suitability of the fish you are planning to purchase by checking here and by careful review of
www.wetwebmedia.com which is a good source of info.
Make sure YOU see the fish you are planning to buy eating at the LFS and that there are no spots, tears or redness.
You can add a couple of hermit crabs. They are predators on some of the good stuff in your tank but are fun to watch and a couple won't hurt. Add no more than 10 snails as well. Acclimate them very slowly. Ask how if you don't know. Avoid bumblebee snails and astrea.
To be successful and avoid most of the problems you read about here like fish death, cynobacteria and algae, you need patience. Go slow and good luck and thanks for posting.