KDE 4.0 is the innovative Free Software desktop containing lots of applications for every day use as well as for specific purposes. Plasma is a new desktop shell developed for KDE 4, providing an intuitive interface to interact with the desktop and applications. The Konqueror web browser integrates the web with the desktop. The Dolphin file manager, the Okular document reader and the System Settings control center complete the basic desktop set.
KDE is built on the KDE Libraries which provide easy access to resources on the network by means of KIO and advanced visual capabilities through Qt4. Phonon and Solid, which are also part of the KDE Libraries add a multimedia framework and better hardware integration to all KDE applications.
First you need to edit the /etc/apt/sources.list file