You need 100% pure ammonia with nothing else in it. Just ammonia and water. You can purchase it at Ace Hardware for around 3 bucks for 32oz. Use this
calculator to figure out how much to dose.
A cycle can take anywhere from 2 weeks to a couple of months. Each tank is different. If you can get some filter media from a healthy established tank it will help it along faster.
If you are doing a fishless cycle, you don't need to do any water changes unless you get a sharp drop in pH, or your ammonia or nitrites go off the charts. If all the parameters stay steady throughout the cycle, you'll need to do around a 90% once your cycle is complete.
Do you have a test kit? Is it strips or the liquid kind?