PNG Backround

[iphone747]

hi@all,
i have a litte problem. At the moment I am working on a little Flex project. An now i have a question. How i can import an .png backround??

I see that it is possible to do that at the style exploer from Adobe. Flex 2 Style Explorer

If you go on "Backround Image" you could select a few backrounds. And on the right side you can see the script.

Application {
   backgroundImage: Embed(source="assets/backgrounds.swf#tartan");
   backgroundSize: 100%;

I tried it to paste this code on the head

   backgroundSize: 100%;>

but it didn`t work.

I hope that anybody could help me with my problem

Thanks a lot