Solar Sail I almost complete!

[Baron Munchausen]

Tacking is not a mystery. By sailing at an angle to the wind the keel of the ship is used like a rudder. Have you ever done kayaking or canoeing? You can make a canoe go 'sideways' in a current by paddling a certain way. It's the same principle as tacking. Since the relative power/weight ratio is much higher with sailing ships than with canoes this is rather slow when you want to go directly into the wind as you have to zigzag, but it's fairly effective when you just want to go at a smaller angle from the prevailing wind.

In space, I think the closest analog to tacking is actually 'slingshot' passes around planets. By controlling the angle of your approach to a planet you can change your final direction to almost anything.