Every Word document has a header and footer. They are blank by default.

Do not use the gallery entries if you want anything special. Instead use Edit Header or Edit Footer and put in your own page numbering fields.

The page number field shortcut is Alt-Shift-P. If you press Alt-F9 you will see it as { PAGE }. You may also want the { NUMPAGES } or { SECTIONPAGES } fields.

Pressing Alt-F9 again toggles these back to show results. Note that the braces {} cannot be typed from the keyboard. You need to use Insert Field or Ctrl-F9 to insert them.

Sections / Headers and Footers in Microsoft Word 2007-2013

Note every section in a Word document can have up to three headers and three footers.