To cycle you need a test kit.. don't try to cycle without one. You really need a test kit even if you use bottled water because that has nothing to do with testing. Test kits show ammonia in your tank. You have ammonia in your tank because of fish poo and uneaten food.. thats why uncycled tanks HAVE TO HAVE weekly to biweekly 100% changes to remove the toxic ammonia in the water.
You cant see the ammonia, nitrites, or nitrates.. they are chemical molecules. Cycling produces bacteria called nitrifiying bacteria that are microscopic. These bacteria absorb the ammonia and nitrites and produce nitrates as waste. Nitrates are safe for fish at levels of 5-10ppm (parts per measure). After these bacteria have colonized in your gravel and your filter they start transforming the ammonia from fish waste.. making the water safer for the fish.. this is why cycling is sometimes referred to as "establishing the biological filter".. it is also why cycled tanks need less water changes.. because the bacteria makes it safer to do less frequent water changes.