You can install Ubuntu Tweak using the Ubuntu Tweak Stable PPA.
Ubuntu Tweak is an application to config Ubuntu easier for everyone. It provides many useful desktop and system options that the default desktop environment doesn’t provide. With its help, you will enjoy with the experience of Ubuntu! Visit the Ubuntu Tweak Homepage.
To add the PPA and install Ubuntu Tweak open a terminal window (press Ctrl+Alt+T) and copy+paste the following lines:
sudo add-apt-repository ppa:tualatrix/ppa -y
sudo apt-get update && sudo apt-get install ubuntu-tweak -y
When Ubuntu Tweak is installed you can close the terminal window and to start Ubuntu Tweak press the SuperKey and type: ubuntu tweak