Update: This is an old article. Please read this article to learn how to install themes in Ubuntu 18.04.
Ubuntu by default comes with Ambiance theme and few other themes like Radiance etc. But these themes are not the best out there and you may want to experiment a bit with the appearance of your computer by installing a new theme but often wonder how do I install a new theme in Ubuntu 12.04. This simple tutorial will teach you to install a theme in Ubuntu 12.04 with Unity desktop environment. Follow these simple steps:
Download the theme. If it is zipped, extract it and copy the theme folder to the following location:
If you are using the graphical way to copy it, go to your home folder and on the top panel select View and then select Show hidden files (Ctrl+H). Now you can see .themes directory in your home directory. Copying the theme is equivalent to installing a theme.
Once you have copied the theme in correct place, the next step is to use the newly installed theme. To activate the theme we will use a wonderful tool “My Unity” which is a Unity tweaking tool and can be used for various other configuration changes such as launcher, dash, panel etc. To install My Unity use the following command in terminal (Ctrl+Alt+T):
sudo apt-get install myunity
Once you have installed the My Unity app, you can open it and move to Themes tab. Here you will see all the themes available in ~/.themes directory. Just choose your favourite theme here.
Voila! You have a brand new theme installed on your computer. Cheers :)