This is known as the "Dock". It will be found at the bottom of the desktop (opening screen).
Click on "System Preferences"

Click on either one of the "Network" icons

Click on the "TCP/IP" tab.
Enter DNS numbers in the "Domain Name Servers" text box.

Click on the "PPP" tab.
Enter Details.
Click on the "Apply Now" button.

Click on the "Save" button.