20 years old and no one ever taught me...

I'm embarrassed to say I'm 20 years old and only recently became sexually actively and still don't know when women are more fertile. Is it the week after their period, 2 weeks or 3? I know you aren't during your period but I've never known the answer to this and I've never actually really thought about it. Please no judgment, just help me with the answer if you know it please! Thanks 😊