How to Restrict a website in Ubuntu Os

How to block or restrict a website in Ubuntu opensource Operating system, without any other third party software, with simple and easy way:

Press Alt+Ctrl+T for open the Terminal and

Take super user access with command 

01- desktop@desktop:$ sudo su

asking password so type password of your desktop computer

02-desktop@desktop:# sudo gedit /etc/hosts

there will pop a text file, in the end of the file type 

127.0.0.1      www.websitename.com (www.google.com or www.facebook.com)

www.websitename.com is name of a site which one you want to block... 
Look like this...

or

edit file in terminal  

desktop@desktop:~# nano /etc/hosts

once restart the networking service or connection. like plz...