The best way to install and configure a Symfony2 project is described in the official documentation as follows:
Mac OS X / Linux
$ sudo curl -LsS http://symfony.com/installer -o /usr/local/bin/symfony $ sudo chmod a+x /usr/local/bin/symfony
c:\> php -r "file_put_contents('symfony', file_get_contents('https://symfony.com/installer'));"
Then you could use the Symfony binary to build the right scaffolding:
$ symfony new my_project
Now you can create a new Symfony project with composer:
composer create-project symfony/framework-standard-edition my_project_name
This will create the project in the current directory you're in.
If you want to create the project with a specific version of Symfony, you can add a parameter with the version number:
composer create-project symfony/framework-standard-edition my_project_name "2.8.*"
Hint: If you're thinking that composer won't do anything, add the
-vvv flag to the command. That way, you'll receive detailed information about what composer is doing right now.