I just had a read through the tutorial, good stuff there.

There is another way to drop in custom images into WD9 and WD9P and this works from the bitmap gallery, the fill Gallery and even Windows Explorer. Hold down the Ctrl key on your keyboard and drag and drop. Drop onto the pasteboard background to set the image as a tile and it will automatically tile on the pasteboard background, Drop onto the page and it will tile on the page background.

Edit: I forgot to mention you can Ctrl Drag and Drop an image that is larger than the page onto the pasteboard background and it will be centred and it will be scaled to fit the browser window!