Go to Start and then Run.Type in thisC:\WINDOWS\system32\drivers\etcNow you will see file nameHost open that in Notepad.Below "127.0.0.1 localhost" add IP address of site to be blocked.To unblock any site justreversed the process. EXAMPLE
127.0.0.1 localhost 69.171.224.14 (This will block Facebook)
NOTE: For each site you block just add "1" to the IP (127.0.0.1)