2 - Double-Click on the "Network" icon:

3 - Go to the "TCP/IP" tab. If your computer is configured to use a dynamic IP address, you should see a screen like this one (notice "Using DHCP" in the drop-down box next to "Configure"):

This is where you can change your DNS settings, by entering the appropriate DNS servers in the "DNS Servers" box.

Enter the OpenNIC DNS, preferrably the most near your location.

Apply your settings by clicking the "Apply Now" button and Done!

You should now be able to visit the Main OpenNIC Project Site. In addition to other OpenNIC Sponsored Top Level Domains you also have access to all alt-root Peer Top Level Domain as well.