i installed phpstorm and write a html program but each time run it this address "file:///C:/Users/Saeedeh/PhpstormProjects/it/it.html" is shown. how can i change it to localhost.
Have a look at this article incase you have not seen it yet: http://confluence.jetbrains.com/display/PhpStorm/Installing+and+Configuring+XAMPP+with+PhpStorm+IDE
That message means that browser is having problem with contacting your web server (most likely, since it's network related).
1) What URL is requested?
2) Does it work if you type URL manually in the browser?
3) Please try 127.0.0.1 instead of localhost -- will it help?
What do you have at "Settings | Deployment | Options --> Upload changed files automatically to the default server" ? Quite likely you have fortgot to enable it (value should be other than "Never")