You have to use the mapping elements (one-to-one, one-to-many etc) in the hbm.xml configuration file. For more details check the Hibernate site, hibernate.org.
Cheers, Raj.
Do not meddle in the affairs of dragons - for you are crunchy and good with ketchup. Crunchy tiny ad:
a bit of art, as a gift, the permaculture playing cards