* Goto Google.com and login into your Google account.
* Click ‘Change Background Image’ button at bottom left part of Google homepage.
* Then select image for displaying as background from public gallery or from your Picasa photo albums. You can use images with minimum 800X600 resolution of either format: JPEG, TIFF, BMP, PSD, RAW.
* After making photo choice, click Select button to display that image as background wallpaper on Google search homepage