Cycling is about establishing a colony of nitrogen-fxing bacteria in your tank. This usually takes a few weeks....
You need an ammonia source, to get the bacteria to settle in and grow. Ideally, use a few pinches of fish food or -- if you can get pure ammonia without
surfactants -- that's great! Let ammonia build up to 2-3PPM (you need a test kit to detect this -- use the liquid one, NOT the paper strips).
Now -- if you're patient -- you can wait for the bacteria t settle in (they do this by themselves) or you can speed up the process. Ideally, get filter media (sponges, etc) from an established tank. Or at least get a cup-ful of gravel from an established tank.... this will speed things up. Some people swear by 'bottles' bacteria, but not everyone agrees they work. I used Seachem 'Stability', and it took 4 weeks for my tank to cycle -- about as long as it should take anyway.....
Monitor your ammonai, nitrites, nitrates (you'll need test kits, I'm told the API Master kit is good value). You should first see ammonia going up, then down while nitrites go up. Finally, both ammonia and nitrites should hit zero, while nitrates go up. When this happpens, your tank is 'cycled'. You can now add fish,,,,