Replace "theUserName" to the username relevant to your database, and "thePassword" to the password for the account you set up. Refer to the documentation of your database for details on this. Edit orion/config/data-sources.xml and add the following under <data-sources>:
<data-source
class="com.evermind.sql.DriverManagerDataSource"
name="forum"
location="jdbc/SKForumDS"
xa-location="jdbc/SKForumDSXA"
connection-driver="org.gjt.mm.mysql.Driver"
username="theUserName"
password="thePassword"
url="jdbc:mysql://localhost/forum"
inactivity-timeout="30"/>
<data-source
class="com.evermind.sql.DriverManagerDataSource"
name="forum"
location="jdbc/SiloDS"
xa-location="jdbc/SiloDSXA"
connection-driver="org.gjt.mm.mysql.Driver"
username="theUserName"
password="thePassword"
url="jdbc:mysql://localhost/forum"
inactivity-timeout="30"/>
and add the mysql jdbc driver to orion/lib.