If you use the starters-kit you dont have to configure something and you should have a look at the GettingStartedGuide. There you find much help.
It is no problem to integrate JBPM in your own web application. You have to modify the hibernate.config.xml to your needs and some lines in the jbpm.config.xml. I had no problems with it. I used JBPM3.1.2 in my own web app on a MySQL database.
For the database, there are several create-script for different databases in the starters-kit .
Thanks very much, Froschfinger.
But your response has nothing newer than what I can find on JBoss Web site and the official documents dealing with jBPM.
My question is : What if I do not like using the starter kit and that I have a big Entreprise EJB3.0 application pre-configured to run with JBoss-4.0.5, and want to intégrate jBPM with all that stuff (an existing JBoss configuration an existing Database, ...)?
Solving this problem is not very different from e.g. trying to run jBPM with Tomcat. There is lots of info on this in this forum and in the wiki.