ActionScript 3.0 :: Flash Bringing In URL Dynamically From XML File

I am new to AC3 and I need to have my Flash movie read URL's dynamically from an XML file. I have used this code and applied it to my button(photo_link_btn):

photo_link_btn.addEventListener(MouseEvent.MOUSE_D OWN, mouseDownHandler);
function mouseDownHandler(event:MouseEvent):void {
navigateToURL(new URLRequest("[URL]"));
}

It works when I hardcode a URL into the URLRequest line highlighted above. But I am trying to bring in the URL through XML. Here is an example of the XML data:
<?xml version="1.0" encoding="utf-8"?>
<photos>
<photo>
<filename>animals_400x260_01.jpg</filename>
<title>House</title>
<description>Description:</description>
<link>[URL]</link>
</photo>