You need to cycle your tank.
You see when fish eat food, they excrete nitrogenous wastes as ammonia. Unfortunately, ammonia is highly toxic to fish. Now the right kind of bacteria can convert ammonia to less toxic nitrite and then to relatively non toxic nitrates. This beneficial bacteria will live attached to rock surfaces.
You can get bottled ammonia at many local fish stores, LFS. So you follow directions and add enough to give you 2 ppm ammonia in your tank. You will also need test kits for ammonia, nitrite and nitrate. Commonly available test kits are made by API, Red Sea and Salifert. Many people just toss a raw shrimp in their tank to serve as a source of ammonia.
You want your tank to convert 2 ppm ammonia completely to nitrates in 24 hours.
At the end of the process, your tank will have something like 20 ppm nitrates or more. Since nitrates are plant fertilizer many people end up with piles of algae growing in their tank. Nitrates can be lowered in your tank water by doing several large water changes. Many people like having nitrates below 10 ppm and I like mine between 1 and 2 ppm.
Now as to your results, you want zero ammonia. Ammonia is really toxic. But your tank is producing nitrates so it is making progress in the cycle. But it still has to progress farther.