configuring printer

you can simply open synaptic package manager ( System -> administration -> Synaptic Package Manager) and click the search button and type:
kubuntu-desktop
click ok. when search complates you will see kubuntu-desktop package listed. right click on it and select "mark for install". it will ask you extra packages will be installed. click ok and click apply.

you can do this using terminal to:
open a terminal
type this command:

sudo apt-get update

hit enter it will ask you for root password. type root password and hit enter. after the task complated type this command:

sudo apt-get install kubuntu-desktop

it will ask you if you want extra packages get installed. hit y and hit enter. it will download and install KDE desktop.

Thanks, Ali, but I did it and I've received an error message (spanish):

kdesktop:
  Depende: kdebase-bin (=4:3.5.2-0ubuntu26) pero se va a instalar (you are triyng to install ) 4:3.5.2-0ubuntu27

try this command to fix dependency problems:

sudo apt-get -f install

then update package database with:

sudo apt-get update

and try this command again:

sudo apt-get install kubuntu-desktop

i hope this helps

Thanks Ali KIBICI, that solved my question.