1) Open up SMBPrefs.
2) Tap where it says Themes.
3) Select a theme.
4) Scroll down to the bottom of the main menu in SMBPrefs and tap "Restart SpringBoard"
Installing SummerBoard themes
To install SummerBoard themes you can download them like an application via Installer.app, but if you have a theme of your own you can install them by SFTP.
You can download Fugu to SFTP.
Connect to your iPod Touch via SFTP, and navigate into /Library/SummerBoard/Themes where you'll see the directories of the four pre-installed themes. Once there upload your theme folder.
The path should be /Library/SummerBoard/Themes/
Now return to your iPhone’s home screen (press the “Home” button) and launch SMBPrefs, then press “Theme” and select “