Simple Flash banner ad

I am working on an advertising site and I need Flash Source code which can be used for clicking ads. I want people to supply me with their flash animations and then I would like a Flash swf which goes on top of their ad and is used for going to a URL. I've heard that it's possible to stack 2 swf's on top of one another, so I'd like their ad below and my clickable ad on top. The clickable ad should be 468x60 and it should go to a URL from a text file called "[login to view URL]" - So when it loads it gets the URL from the text file and then when you click on the ad it goes to that URL. Obviously the swf should be invisible so you can see the ad below it. I would also like it to be easily adapted to different sizes. I have Flash CS5 but I know very little about it. I would also like the HTML to put both ads on top of each other. Also, the HTML needs to work as a php include. I will not have access to the tags on the page this will be on (since it will be a phpinclude). I figure this is quick work for anyone that knows what I'm talk about.