path: root/security/ossec-hids-local/files/message-header.in

All the files related to OSSEC have been installed in:
%%OSSEC_HOME%%

You need to create main configuration file:
%%OSSEC_HOME%%/etc/ossec.conf

For information on proper configuration see:
https://www.ossec.net/docs/syntax/ossec_config.html

To enable the startup script add ossec_hids_enable="YES" to /etc/rc.conf.