Looney Labs (which I am not affiliated with) has resources for learning the rules of Homeworlds. Currently they have a video format and a rules document:
(Seriously, if you haven't already, you should check them out. The pieces you see in the video are an entire game system.)
Please also see How This Site Works for more on the specifics of this website.
But if you prefer to learn by DOING, then... I have this interactive tutorial feature. It is not very polished yet. (I am not that good at user interfaces.)