How to use ovulation sticks

Danielle

Might sound stupid but can someone give me advice/tips on how to use ovulation sticks and which ones to buy? I have NO idea where to start with them. My periods are just so irregular it's driving me up the wall. I've not had a period since the start of December and AF came yesterday despite having lots of unprotected sex in between 😔😔 any advice would be so appreciated x