You might have noticed in the OpenDJ/bin directory a tool called create-rc-script. As you probably guessed, you use this tool to create an RC script, as in
sudo create-rc-script -f /etc/init.d/opendj -u mark.
On distributions like Debian or Ubuntu, for example,
sudo update-rc.d opendj defaults then arranges to run the script when runlevels change, in effect starting the server at boot time and stopping the server at shutdown.
Unless you run OpenDJ as root, make sure you use the
-u userName option.