Yes, I also get 403 Forbidden error when browse http://ipaddress/domjudge
Is the path /home/....... readable for the webserver user? It should probably have world-readable and executable permissions. Also for any subdirs on the path to your DOMjudge directory.
(This is more about generic Apache configuration than DOMjudge configuration. You might want to try and Google some on that as there are many results you can find for configuring Apache and problems with that; this might be quicker than waiting for our replies.)
Cheers, Thijs