How to block a website in win 7

[BABLUKUET]

I can't block a website by the following procedure of win xp in win 7.In hosts file of win 7 gives no permission to save anything.Please can you tell me how to block the website?

 

[The_Prophecy]

Tried modifying the hosts file?

 

[xsever]

You have to right click on the host file first and uncheck "Read only".

Then, you will be able to save after editing it.