• Initialize the database in Postgre with the necessary table structures. (Refer to mysql's jwdb-empty.sql in \data folder in your Joget)
• Get the jdbc driver from http://jdbc.postgresql.org/download.html
• Put it in \webapps\jw\WEB-INF\lib
• Restart Joget
• Go to Joget web console, configure the data source profile accordingly. (Make sure you enter the correct driver class for Postgre)