As Kristy stated, you are referring to a watermark. You can put a watermark on your sheet programmatically, but as an alternative see if your printer can do watermarks.
This is what I do when I want a watermark (using an Epson Stylus):
Excel’s File menu | Page Setup.
In the Page Setup dialog box, click the button named “Options…” - this accesses the printer’s Property dialog box.
Click the tab “Page Layout” (or something similar with your printer).
Click the Watermark’s drop down menu and select an option (“Draft”, “Priority”, Urgent” etc.). If I don’t like any of the options, there is a facility to import my own.
Click the “Settings” button – select the watermark’s colour, position (center, top right etc.), intensity, and size.
That’s it, very simple. It takes about 10 seconds to set up.
Regards,
Mike