Have you changed any of the water? Did you cycle your tank before you added fish? If not, that is most likely the problem. The ammonia and nitrite should be 0, and nitrates should be between 5 and 40
ppm. I would recommend getting a liqiud test kit ASAP. Until then, start changing the water 25-50% every day until you get one. I will try to find the link for the explanation of the nirtogen cycle.