So, sounds like you need to read up on the nitrogen cycle in general.
Simplified, your fauna produce ammonia when they digest food and expel waste. Excess food is also broken down by bacteria and the end product is ammonia. When plants die, same.
Ammonia is broken down by one family of bacteria. For every unit of ammonia, they’ll produce 2.7 units of nitrite.
Another family of bacteria breaks down nitrite onto nitrate; this bacteria takes much longer to grow into a viable colony. 1ppm ammonia => 2.7ppm nitrite => 3.6ppm nitrate.
When I cycle a new filter, I will take a piece of filter media from another, established filter and place it in the media tray of the new filter. I’ll then dose ammonium chloride until my ammonia test reads 3ppm. The bacteria will digest it, multiply, and spread. When the ammonia test reads 0, I’ll dose 3ppm more. Eventually the nitrite consuming bacteria catch up and you’ll start getting nitrate.
I do this until I can dose 4ppm ammonia and there’s no sign of ammonia or nitrite 24hrs later.