What can I do to make the High levels of ammonia and nitrite go down?

When there are ammonia & nitrites in your tank, it means that your tank is not fully cycled. When it is fully cycled, you will begin to see some nitrates, but this also needs to stay under 10ppm.

While your tank is cycling, make sure that you do a 50% water change every week, more if your tank is over-stocked, too small, or not enough filtration.

Also, when you add new water to the tank, make sure that you add the recommended dosage of water conditioner such as Prime or Amquel+