Browser size controls movieclip

I want a movieclip in my swf file that will float a given number a pixels from the left side of my browser window. I have made my swf file trasparent and things outside of my stage show up and so far I have an actionscript code that will only use my stage size and I want the browser window size to control it. Please help, I’m not sure what to even be searching for.

Thanks
Ashley