Creating Popup Windows - Add A "Close Window" Button On Survey.html Page

I read about window object and specifically about creating popup windows. The code below produces a popup window when a link is clicked:

Code JavaScript:
var Survey =
{
init: function()
{
var surveyLink = document.getElementById("survey");
Core.addEventListener(surveyLink, "click", Survey.clickListener);
},
[Code]....

I would like to add a "Close Window" button on survey.html page and when that button is clicked, the window would close. How do I do that? I know that I should use (reference to popup window).close(), but how and where do I attach even listener to that button?