First you should reach tau 23, the cali base to be precise. It should be on your map from the SP missions. Ok so when you're on cali, the map won't show you anything but cali and some star. YOu should set a waypoint close to that star then a waypoint to the upper end of the map (I'm talking about the nav map). You should then find the tau 37 jump hole and then start exploring tau 37. There you should find your jump hole to Omicron Alpha. The gates to beta and theta are in Omicron alpha. I don't remember the exact co-ordinates, but you should be able to find them if you explore. I have to tell you I enjoyed exploring those places a great deal and I am not finished yet. One thing though. Cali is an OUtcast base, so you should better be friendly or at least neutral with those people.

Ok. I'll end here, because you may already know some of this yourself and I don't want to bore you with unnecessary details. Hope it helps. If not, then maybe someone else would point out a better solution

Keep on freelancing