watermark in calc pages

From a Sheet i “export as PDF” a printet area .
I want add a watermark text or image
how can do this?

Does your exported page include only 1 or more than one pages? First case would be easy (insert an image; reduce opacity).

If there are more pages the easiest way could be to import the pdf in LibreOffice draw, add the watermark, export as pdf again…

I think (but I’m not entirely sure) there is no way in Calc to use headers/footers for this purpose.

Thank you !!
But i need for more pages and i think no exist solution to this problem…