In this tutorial we gonna discuss how to install gnome 3.12 on a existing gnome dekstop edition.
Gnome project has recently release GNOME 3.12 .

Major features for this release include:

• A significant update to the experience for finding and installing applications.
• Major facelifts for the Videos and gedit applications.
• Greater high-resolution display support.
• Big updates for the Software and Web applications.
• Improved start up times as well as more efficient resource usage.
• A new application folders feature, which lets you organize your apps.

1. To Update from current Gnome Shell 3.10 to 3.12. We need to add repository, Open a terminal and run the following command.

sudo add-apt-repository ppa:gnome3-team/gnome3-staging

2. To Upgrade Gnome Shell 3.10, just run the following command on terminal.

sudo apt-get update 
sudo apt-get dist-upgrade

3. After you installed update or upgrade we need to reboot the system and run the command on terminal with root privileged/sudoer.

reboot

Credits to: http://www.gnome.org
 
Enjoy….