In the Symfony 2 tutorial we are supposed to "run the following command":
php app/console init:bundle "Acme\StudyBundle" src
What they don't say is how to do it (where?)
You should do this from the Symfony2 root directory (eg where you have 'app', 'src', 'vendor' and 'web') (if what you meant was "from which dir").
If you do not know how to execute this command, you have to type it in a terminal after using 'cd' to get to the right directory.