Show interstitial by clicking on screen


Hello friends, so far in my app the interstitial advertising showed it every xxx seconds by means of a clock, that is to say every xxx seconds the interstitial was shown and when closing it again the clock will be executed.

I have an app that is a webview and I would like that instead of showing the interstitial for seconds, it will be shown for example by clicks, that is, every xxx times the user clicks on the screen the interstitial is displayed. I’ve been looking for but I don’t see how to do it, I’d like help, thank you very much.