Canon LBP7210Cdn Manual page 309

Select a watermark.
(1) Display the [Page Setup] sheet.
(2) Select the [Watermark] check box.
(3) Select the character string to be printed as a watermark.
NOTE
If you cannot select the [Watermark] check box
If [Spooling at Host] in the [Device Settings] sheet is set to [Disabled], [Watermark] is grayed out
and cannot be specified.
See "Changing the Setting for Spooling at Host"
[Auto].
Confirm the settings, then click [OK].
The [Print] dialog box reappears.
and change the setting for [Spooling at Host] to