how to block some websites in your PC

your childern wasting time by opening by chatting,posting scraps in orkut or opening illegal then stop that websites in in your PC by doing like bellow .first open My computer/c:/windows/system32/drivers/etc folder,open HOSTS file in notepad format and add a line in bellow of 127.0.0.1 local hostline and write a line 127.0.0.2 www.orkut.comas shown in above figure .if you want to stop another website then add one more line bellow 127.0.0.4 www.gmail.com and save file dont forget it