wow thats funny question,

but its good that you asked if you don't understand, basicly...
Starboard = Right
Port = Left
So, (riding healside or 'normally') if your riding on a port tack your left arm will be in front. If your on a starboard tack your right arm will be leading.

Make sure you go to this link
http://www.ikorg.com/priority_rules.php?menu_id=5