I would like to know how to insert a image in the header for all pages of a document in Acrobat Pro XI, please.
Excuses my english language is not good.
Open the Tools Panel, select Pages > Background and "Add Background" from the dropdown menu.
You can then open a file in the Add Background dialog with your image and set its' position. When you are done it will by default apply that image to all pages.
Europe, Middle East and Africa