momwannabe81 explained it great.
With me I judge basically by how far I have to go in to find it. Once you start checking it everyday you will get what im talking about. You will feel the difference from low and high and everything in the middle. When its firm it feels more like the tip of your nose, and when its soft its more like your lips. Open vs close is the most difficult part. Like momwannabe81 I still have difficulty figuring that out. If your cervix is high soft and you have your EWCM you are in your fertile period.
Like I said once you start checking it regularly you will know what high, soft, low, firm and all that stuff feels like in your body.