You probably did change the rudder too quickly. Every time you change the
rudder position, this results in a drag (due to imbalance) and the boat has
to find balance back (by turning). If you move the rudder too fast and too
far, the result of this imbalance is that the boats starts to stall. Then
you'll end up in irons (straight into the wind, no speed, no control).
If you're sailing with the jib, then leave it in position (assuming you
first attempt sailing close hauled (as far as you can into the wind. About
45 degrees off actual wind) until after the wind grabs it from the wrong
side (now you are straight into the wind), as this will help pushing the bow
through the eye of the wind. Also let the boat come close to beam reach (90
degrees on the actual wind) after the tack before attempting to sail clause
hauled again (if case you try to go upwind).
It is a bit hard to explain all by writing how to tack and there is a big
part of your own experience that comes into play as well.
Most important is to get some cheap old sailing book or some documentation
from online. There is much to learn this way and it is very helpful.
Fair winds and good sailing!
Albert.
Ps: Currently looking for a stable and easy catamaran like Hobie Getaway.
Harder to tack, but hopefully allows me to get my windsurfing feeling back
(when using harness) and allow my wife to join me!