PostgreSQL with Oracle OC4J Application server

Dear Postgresql experts,

First i want to mention that i'm new to postgreSQL DB.....

I have a J2EE application  which is deployed on Oracle OC4J application
server and Oracle 9i DB i'm trying to migrate to PostgreSQL DB (cost
reduction issues....)
so I have installed PostgreSQL 8.0.1 on win 2K platform and and iv'e defined
a small DB (just for test...).
my next step is to configure it to work with OC4J (DataSource
configuration).....and i couldn't find any documentation on it.... 

does anyone know how to do it ?  

appreciate any help -:)

thanks in advance
-sharon