define "networking" please. it is a pretty broad term so we need to know roughly what you're trying to achieve here. if you're after SMB file sharing (a.k.a Windows File Sharing) then you need to download the samba packages. off the top of my head i think you need to install samba-common, samba-client and samba-server. just use sudo apt-get install name-of-package or use synaptic to install them.
actually come to think of it i think if you find the option for file sharing in the system>administration menu it can automatically install the required packages.
edit: sorry i'm not quite sure about the options in KDE, i'm a long time GNOME, Fluxbox and XFCE user.