Kubuntu Linux : Connecting to Internet

To connect to the Internet, do the following:

1. If you have a Modem or ADSL connection, read the section called "Modems" first.
2. K-Menu->System Settings->Network Settings
3. Click on the Administrator Mode... and enter your user password to gain administrator privileges.
4. Select the Network Interfaces tab. Select the interface to configure from the list, then click the Configure Interface... button.
5. Enter the relevant details of the connection like DHCP or Static IP address, or the wireless network name (in case of a wireless connection). Click OK to accept the settings.
6. Sometimes it may be necessary to configure the DNS settings. If needed, select the Domain Name System tab to add edit or delete DNS Servers in the DNS Servers list.

To activate or deactivate network connections, do the following:

1. K-Menu->System Settings->Network Settings.
2. Click on the Administrator Mode... and enter your user password to gain administrator privileges.
3. Select the Network Interfaces tab. Select the interface to enable/disable from the list, then click the Enable Interface or the Disable Interface button. 

Reference :- http://linux.about.com/od/kubuntu_doc/a/kubudg29t02.htm