A background appears behind text or images on the page. The background can be as simple as a solid color, or you can use an image. You can selectively apply a background to only specific pages or page ranges in one or more PDFs. A PDF supports only one background per page, but the backgrounds can vary from page to page.
Choose Tools > Edit PDF.
The Edit PDF toolset is displayed in the secondary toolbar and other related options are displayed in the right hand pane.
If a message appears, telling you that the current document already has a background, click Replace Background. If you apply the new background to a limited range of pages, the old background remains unchanged on pages outside that range.
To reuse a background and background options that you saved in an earlier session, select it from the Saved Settings menu.
To apply a solid color background, select From Color. Then select a color swatch or custom color from the color picker .
To use an image, select File, then select the image file. To select a specific image in a multipage file, enter it in Page Number.
Only PDF, JPEG, and BMP files can be used as background images.
If the original image file that you are using as a background change, you can update the PDF to show the new version of the image rather than removing the old version and readding the new one.
This process applies only to backgrounds added in Acrobat 7.0 or later.