Assuming you have all the needed annotations and correct getters / setters in your php files, it should be enough to call php app/console doctrine:schema:update --force. For preview purposes ypu can use php app/console doctrine:schema:update --dump-sql. That will show you the sql which will be executed.
If you only have annotated properties without getters / setters (so you have created the php files, added properties which you want as columns and added their respective annotations), first use php app/console doctrine:generate:entities MyBundle/Entity. This will create the getters/setters for you. Check here for additional information.
php app/console doctrine:database:createto create the database and thenphp app/console doctrine:schema:update --force. You can read more in the documentation.