How can I create my database schema when I am developing with ejb3 and hibernate?

Use in persistence.xml:

<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">create</property>

But this is all written in the docs.
Read them?

hibernate tools also provide a ant task for it.

<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
<property name="hibernate.hbm2ddl.auto" value="create"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
none is working. Witout an error message
Could you please lead me to the ant task?

tools.hibernate.org and use a <annotationconfiguration> with a hibernate.cfg.xml which includes the list of the classes you want to have table generate for.