I didn't know too, but if you read "how to install" right in kde-look.org you will know how to do it. There are different ways, it depends on what you are trying to install. Something has only to be added through the KDE control center, somthing else has to be compiled with ./configure, make, make install. It depends, but you will get more detailed informations in the site or directly in the files you downloaded (usually the install file). Hi.