Google Homepage's Theme is available from Google for customizing your Google Homepage. So, here's what to do:
1. If you don't have any customized Google homepage yet, then visit this page.
2. Click the linked phrase "Make It Your Own" and then check those items you want to become available on the customized homepage.
3. On the upper-right side of the page, you'll find "Select Theme". Choose the theme you want and it will be set.