How do I make a SWF file play back with a transparent stage?

I'm new to version 3, and just got started with the desktop version. How do I make the stage of my SWF file transparent so I can display an animated background behind it?

Thanks!

You will need to create a swf with transparency and upload it to the system. You will need to do this outside of our Studio software.

I thought SWF transparency was controlled by html in the playback using a wmode tag. Do I need to create html code to make it work? If so, what syntax do I use?

I thought SWF transparency was controlled by html in the playback using a wmode tag. Do I need to create html code to make it work? If so, what syntax do I use?

You are correct.
Add the following parameter to the OBJECT tag:

 <param name="wmode" value="transparent">

check this guide as well.

http://www.adesdesign.net/php/tutorials/flash/transparent_flash.php