Begin at the beginning
Let's begin at the beginning, moonbaby.
First, when you change water, what do you add for water conditioner? Do you know if your local water has chlorine or chloramine? It is important to use the right stuff, for if you have chloramine and use stuff that only unlocks the chloramine but does not neutralize the ammonia it just adds the ammonia to the tank.
Next, how much are you feeding these fish? How many fish? How many times a day? Too much food is adding a lot to the load of ammonia in the tank, for a fish will eat anything it can and the undigested food just falls out the back end as more is shoveled in the front end. They say to feed as much as one fish eyeball per fish once per day. Are you overfeeding?
If you have been feeding too much, then there is a lot of poorly digested food that is in the gravel rotting away, this will add to the ammonia level in the tank. You'll need to gravel vac to remove that. Don't try to do it all in one day, it may take a few days to get it clean.
Next, look at your filter. The filter is the key to processing ammonia and it needs to be correctly sized and kept relatively clean. What sort of filter do you have? What size and what size is your tank? When was the last time you cleaned the filter? How exactly do you clean it?
Now, and maybe this should have been first, how many fish do you have and what size is this tank? Overcrowding will also make for too much ammonia in the tank.
