What version of Word?
Word 2003 and earlier allow you to do this automatically by choosing Outside
(or Inside) placement in the Insert | Page Numbers dialog. But that dialog
is often not the best way to insert page numbers because it inserts them in
a frame, which can cause problems if you have other header/footer content.
A better way to insert page numbers (and the only way in Word 2007) is to
place them directly in the header or footer. In order to have them on the
inside or outside of the page, you must enable "Different odd and even"
headers and footers. This is done on the Layout tab of Page Setup in Word
2003 and earlier and on the Design tab of the contextual Header & Footer
Tools in Word 2007. You will then have a separate Odd Page Header/Footer and
Even Page Header/Footer where you can place the page number as desired.
In Word 2003 and earlier, you can use the Insert Page Number field on the
Header and Footer toolbar. In Word 2007, the Page Number button in the
Header & Footer group on the Header & Footer Tools Design tab of the Ribbon
gives you a choice of page number building blocks, but if you want to
combine a page number with other content, you need to choose Current
Position (and probably Plain Number).
