On Click Opt In Popup? Please Help!

Hey all,

I would like an optin pop up to appear when someone clicks on the call to action button.

I have an account on mail chimp which I have designed a pop up on but it only lets me choose a time delay before it pops up, as opposed to when someone clicks.

Please can someone tell me how to do this? (even if I have to use a different provider).

PS – please bear in mind I’m an absolute coding noob!