Open the Excel workbook
Go to the worksheet where you want the watermark
Click the Insert tab
Select Header & Footer
Click inside the header area
Go to the Header & Footer tab
Click Picture
Choose the image you want to use as a watermark
Click Insert
Click anywhere outside the header area
Resize or format the image if needed
If you want the watermark on every printed page, keep it in the header or footer
If you want a lighter watermark effect, use a faded or transparent image before inserting it