Link to website with class

Hi

trying to create a link in my flash file to a lightbox/pop-up window. So far it looks like this:

gotopart5.addEventListener(MouseEvent.CLICK, DocClick5);
function DocClick5(event:MouseEvent):void{
navigateToURL(new URLRequest ("http://www........./propel/test.html?height=450&width=620"), ("_blank"));
};

the issue I have is making it somehow call the external class="xx" – which I need in order to make the window actually appear right.

Where/how do I put this class in the flash document? Or do need to do something entirely different.

Thanks in advance!

-Michael