To add the KDE desktop environment to Linux Mint 15
1. Open a terminal window.
2. Type in the following commands then hit Enter after each.
KDE Standard
sudo apt-get install kde-standard
KDE Full Package
sudo apt-get install kde-full
KDE Plasma Desktop
sudo apt-get install kde-plasma-desktop
KDE Plasma Netbook Edition
sudo apt-get install kde-plasma-netbook
Kubuntu Desktop
sudo add-apt-repository ppa:kubuntu-ppa/backports
sudo apt-get update
sudo apt-get install kubuntu-desktop