Branding and Publishing
There are
some final touches that can polish and finish your workbook. The
next few pages describe how to add a watermark, prepare to share
this work publicly, and mark it as Final. You will also learn how to
set the security and limit access to your spreadsheet.
Try it: Add a Watermark
Select a
sample spreadsheet.
Go to
Page Layout ->Background.

You will
be prompted to browse for a picture file. If you choose a light
picture, you will be able to see your data better. You may wish to
edit the brightness and contrast in a photo editor BEFORE you select
a picture for the background.