View | Header and Footer. Double-click on the object to bring up its Format
dialog (or right-click and choose Format [whatever]). On the Layout tab,
click Advanced... In the ensuing dialog, set both horizontal and vertical
position as Center Relative to Page.

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Suzanne S. Barnhill
Microsoft MVP (Word)
Words into Type
Fairhope, Alabama USA
Word MVP FAQ site: http://word.mvps.org
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> I am trying to add a watermark to a doc file and figured out that you have to
> add it to a header or footnote which I have done. Once I do that, I can't
> move it to the center of the document and make it transparent.