Launching PopUp with Ajax front page upon clicking a button

Hi, I would like to set up a PopUp containing a Contact Forum when the user clicks the contact button on the home page.

I would like the page not to change and remain on the home page but simply the popup is displayed showing the contact form. I had a look through the Displaying options but am unsure which condition should be used in this case.

Popup name - "Contact Us" - https://monosnap.com/file/GZ9rmZgLj7OB7IupiIY3Pw5ZJSCxcX

Domain: http://tinyurl.com/os5qcku
Support access is ACTIVE until August 28, 2015 12:42 pm

Thanks
Tom