Adobe Acrobat 7 Professional - Manual (Page 25)

If you want to add headers, footers, watermarks, and
backgrounds
Choose Document > Add Headers & Footers to add headers and footers. (See Adding
headers and footers .)
If your document in the original application includes page numbering, those page numbers
appear in the PDF document. When you remove pages or combine several PDF
documents, page numbers may be out of sequence. However, you can add headers and
footers to PDF documents, allowing you to add page numbers or other information
specific to the PDF document.
You can also add watermarks and backgrounds. A watermark is text or an image that
appears over existing content when a document is viewed or printed. A background is a
color, texture, or pattern behind text or images. Choose Document > Add Watermark &
Background. (See
Adding watermarks and backgrounds .)
Add headers and watermarks to a PDF document after it's created.