This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I would like to see a more specific question. I'll leave this here anyway:
Since you already have a database, a great way to get started with Hibernate is to point it at your database and tell it to build entities for you.
most of the tutorials show how to do this with Eclipse, and I guess that is fine if you are already comfortable with eclipse, but doing it from the command line might be better depending on where you are at.