1. To update dns you need to open your local network setting. Please see your local area network connection near the system time in task bar. (If you can't see then Goto control panel --> click on network connection --> Right click on your internet connection --> click on properties). Right click on network connection icon in task bar --> click on status
2. you will see status dialog box, click on properties
3. In general tab, click internet protocol tcp/ip and click properties button
4. you will see another dialog box, On general tab, click on option button "Use following DNS server address"
5. add value 208.67.222.222 and 208.67.220.220 OR for Google DNS 4.2.2.1 and 4.2.2.2
6. click on OK
Now your computer will use Open dns.