How can I know when I'm most fertile??

Hi guys,

Hope everyone is having a nice Thursday.

I just want to know how do you track when you’re most fertile?

I got my period yesterday on July 5th

My period is normal and usually lasts 5 days.

I get it every month but I’ve never tracked my fertility and want to know the optimum days when I can get pregnant. How do you do this?

I downloaded a bunch of fertility tracking apps, but some of them say different days…

If I got my period on July 5th, when would I be most fertile?

Is it really 10 days afterwards? 2 of the apps are saying I’ll be most fertile on July 16th…........

Anyway this is the first time I’m trying to see my fertile window so any tips help! Thank you!