At first I should admit that this article is something childish but I hope this will help kids and newbies to know more about Google features that aren’t used most.
The default background of Google homepage is white, you can make it colourful with images. Set a background picture on your Google search homepage and your background picture remains the same on any computer when you are logged in with your Google Account.
Find “Change background image” option in bottom left of the Google Homepage and click it to change the background image. You can select image from public gallery or your Picasa web photos.