Don't feel badly, it took me and a lot of others a long time to understand it.
Your tank needs a source of ammonia to cycle, whether it's from pure ammonia or fish food. It's preferable not to cycle with fish because ammonia and
nitrite are toxic to your fish.
The goal of cycling is to develop enough beneficial bacteria to 'eat' the ammonia as it is produced keeping the ammonia and nitrite level at 0. The byproduct of these is nitrates, which in high amounts is also toxic.
That's why weekly water changes are recommended after the cycle is complete.
Here's a basic explanation of the process:
First your ammonia will rise, in a few weeks you'll see the nitrite levels rise and the ammonia levels start to drop. After a few more weeks you'll see the nitrate levels rise and the nitrite levels drop.
When you having readings of 0 on both ammonia and nitrites with some nitrates showing, your cycle is done.
I hope that helps.