Welcome. To start your cycle, just set the tank up with substrate and what ever else is in it. Fill it and start the filter running. If you don't have a test kit you will need one, but for right now just run the tank 4-5 days and remove and replace 20% of the water. You can also take one or two small flakes of fish food and toss it in. Keep this process up for about 15 days. If you still don't have a test kit, do a 50% water change and repeat the process in 3 days. Don't replace the filter cartridge or filter material, it is a bacteria factory and you need it. Once you get to this point you can put a fish in and see how it does. If fine slowly add the rest.
One piece of advice, go with the largest tank you can as they are far more stable.