Overlaying swf on html pages

I remember seeing a post ages ago about overlaying swf files (particularly adverts) onto html pages.

I did a search, but couldn’t find it so forgive me for asking again. Does anyone know where to find tutorials on overlaying swf adverts onto a html page?

Its something to do with background transparency in the embed tags, i believe.

http://www.kirupa.com/developer/flash5/dhtmlflash.htm

Thanks heaps for that! This should serve for what I’m after.