Similarly to my post about adding colour to individual page's content area background you can also add an image as background. Follow these quick instructions to jazz up your google site ....
1. Upload your image to your google site:
Click on more > Manage > Attachments > Upload your image > Once loaded click on view, later you will need to copy the very long url for the image ... so leave it open
2. Navigate back to the page you would like to add your background image to > Click on edit > Click in the area where you would like your image to appear as a background > Click on HTML > Insert the code found on this page:
Just replace the bold text with your copied image url from step 1 making sure you leave in the surrounding " ".
And of course change the text to your own words.
(To get the url navigate back to your opened background image and copy the url from the address bar.)
3. All You Need To Do Now Is Save! Oh And Enjoy!