I start the tutorial (as newbie) and everythings works fine till:
http://symfony.com/doc/current/book/page_creation.html#creating-a-page-route-and-controller at step
http://localhost:8080/SymfonyProject/web/app_dev.php/lucky/number
It works for me. Change "SymfonyProject" with your project name folder or delete it if your project is pointed directly by the Server. Also pay attention to the port that works for you (localhost:8080). In my case is 8080, in your could be 8000 or something else.