Hibernate version: 3.0

Hi, Im a bit confuse about how to build the database schema from bean classes using annotations.. I couldn't find any good tutorial or reference for that.. Here's what I need to do: I need to build de database schema from bean classes ( TOP-DOWN ) using annotations instead of using the hibernate.cfg.xml file.. I think there must be a good way to do this.. CAN anyone give me some help.. I need a good tutorial or a reference... anything will help a lot!
Thanks!!!

tools.hibernate.org - read the ant docs