Little tutorial:
1. Download trial version of Adobe Flash CS5 (30 days full working trial, don't need to buy licence);
2. Create new flash project (AS2);
3. hit F9;
4. In Actions window which will apear, write code:
Code
Stage.scaleMode = "noScale";
Stage.align = "TL";
var my_logo = _root.createEmptyMovieClip("my_logo", _root.getNextHighestDepth());
my_logo.loadMovie("logo_image_path/logo_image.jpg");
Stage.addListener(my_logo);
my_logo.onResize=function(){
my_logo._x = 0;
my_logo._y = 0;
}
5. Save your project in any folder.
6. Click "File" (on top of the flash application) and chose publish.
7. Upload your published swf file as background to your gallery.