I have a white stage and my background is non-solid/non-uniform. My flash project will be my whole website, therefore when a browser window is larger than my stage, the stage color (white) shows in the background. Its basically a white border on the left and right. I wish I could continue my background image to cover the whole browser window. What I want to do is: if needed (if the browser window is larger than my stage) continue my background on both sides by taking a copy of my background image, flipping it horizontally, and placing it on both sides of my background. If you can imagine it, this will give a more uniform continuation of the background. I just don't know how to go about doing this. I'm guessing actionscript would be the best bet?
you'll need to edit your html code. check for tutorials on html background images
If you simply want the background to cover the browser window, but don't really need the wrap arround, you can go to publish settings, and under the html tab set the width and height to 100% (make sure it's set to %, not pixels or any other measurement). This should scale the stage to the browser window. If this doesn't work, then you'll have to edit the html, which I unfortunately can't really help you too much with.