You can personalize your page by selecting Site Settings and then Change Appearance.
Click on the Appearance tab.
Select the Site Elements Tab to add your own personalized logo OR remove the standard Google Sites logo.
Select Colors and Fonts tab to customize the colors used in your web site.
Click on the change logo.
You can upload your customized logo (by clicking Browse and finding the file on your hard drive) or select the No Logo button.
You can also change the Site Layout, click on the button. Here you can adjust the width of the sidebar, entire site, and header size.