1) Open notepad with administrator rights
Open Start Menu, type “notepad” in the search box, right click the notepad icon and select “Run as administrator”

2) In Notepad, open the hosts file
Choose option File > Open from the menu, go to C:WindowsSystem32driversetc and choose the “hosts” file
Note: the “etc” directory will probably be hidden, but you can just press F4 and type the path above

3) Insert your sites
Go to the end of the file and enter a new line with the following format
127.0.0.1 site1 site2 site3
replacing “site1″, “site2″ and “site3″ with the url’s of the sites you want to block.

Example:
127.0.0.1 facebook.com hi5.com myspace.com

You can put as many sites as you want on that line. Just remember to separate them with a space and never press enter (to keep them all on that line).

4) Save the file and close Notepad

5) Open a command line client
Open Start Menu, type “cmd” on the search box and press enter

6) Flush the DNS cache
In the CMD window type “ipconfig /flushdns” and press enter.

This command will clear the dns cache and reload the hosts file.
With this you don’t need to restart your computer after changing the hosts file.

I also advise you to close and re-open your browser.

Hope this helps =)

Best regards,
Latino