Blocking purpose

Hello,
this is anees.actually i block the orkut site on my laptop so no,one can access this site.this procedure is done by the help of security option-restricted sites,its a path but in this process it was show its a restricted sites.
actually i want to block a sites and no messege can show on my laptop screen and nobody can understand its a block sites. so plz send me a procedure hiw can block a particular sites


thanku sir