If you're using a Macintosh, just drag the image from your browswer to the desktop (or hold your mouse button down over the image and select "copy this image" from the pop-up menu). If you're using a PC-compatible machine, hold the mouse over the image and press the right mouse button. Select "save this image" from the pop-up menu. That's it, the poster is all yours. But remember, Warner Bros. still owns the copyright.