how do you know about your cervix

Can someone explain the meaning of cervix low and high and what it meens and how important it is for TTC and what it meens when it's open or closed I always hear people talk about that and would like to see on my self and does it meen the day before your period of your going to start your cervix will be lose ? And if your not going to start it will be tight .... I'm sorry if I sound stupid I really wanna learn this please don't be mean to just educate me on it thank you