OPK for dummies: can someone please help me?

Autumn

Ok, I don’t have regular-regular periods, but I do have one every month, with that being said; when should I test for ovulation. And do I need to keep and date my opk’s to see the test line getting darker? Because I haven’t been doing this.

Also, after you get your positive. Is it 100% that you ovulate 12-36 hours after? And how do you know you have for sure ovulated?

I’m just so confused; I’m sorry I sound dumb.