How to Block Any Website

1.    Open Run Menu & Paste %Windir%\System32\Drivers\Etc

2.    Find The File Named "Hosts"

3.    Open It In Notepad

4.    Under "127.0.0.1 Localhost" Add 127.0.0.2 www.Google.com 
And That Site Will No Longer Be Accessable.

5.     Done!

For Example-

      127.0.0.1 Localhost
127.0.0.2 www.Google.com
127.0.0.3 www.Google.co.in

For More Than One Site To Block-

      127.0.0.1 Localhost
127.0.0.2 www.Google.com
127.0.0.3 www.Google.co.in
127.0.0.4 Google.com
127.0.0.5 www.Yahoo.com
127.0.0.6 Yahoo.com
127.0.0.7 www.Orkut.com
127.0.0.8 Orkut.com
127.0.0.9 www.Youtube.com