First you must download the modified assets, which I’ve packaged as into the following zip file.
Download New Unity Launcher Design Assets -> Save the download file to Desktop.
Extract the contents of the archive and copy (as root) all the items in the “assets” folder to “/usr/share/unity/6″ replacing the existing assets.
Open the terminal:
cd Desktop (or location of download)/raring-design-assets/assets
sudo cp -r * /usr/share/unity/6
For the changes to take effect, you need only log out then back in.
To undo changes or revert to default just reinstall the “unity-common” package through the Ubuntu Software Center or by running the following command:
sudo apt-get install --reinstall unity-common