It depends somewhat on which version of Word (2000, 2003, 2007, 2010 etc.) In Word 2010, go to the Page Layout tab on the ribbon and choose 'orientation', then set 'landscape' instead of 'portrait'. On the same tab, click 'Size'. In Word 2003, it's File, Page Setup to choose orientation, and then in the same dialog box, 'paper' allows you to set the size.
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