How to create a Close Button at the top left corner of a full page FLash file in AS3


I need to create a full page flash file that overlays a webpage. Something like the example in this link.

I have figured out how to create the flash file which will overlay the page, with all elements centered, from here: kirupa forums tutorial.

The only thing I cannot figure out is how to attach the Close button which would come at the top right. AS3 is not allowing me to attach any behaviour to the button, neither does it allow me to put actionscript there. I am in dire straits. Please help…

Thanks in advance.