I used network connection to connect to Internet (Dongle) which automatically detect my device in GNOME but when I Log off to KDE I cannot find networking connection and I cannot connect to Internet, I found only network tool which I can't figure it to connect.
give a right click at your KDE panel at left option after time , it will gives you like this
Among that select System tray settings and it will open a window like this . In this window select Network management in Extra Items .Then you will have network applet at your panel .
By using that you can manage your network connections .