Transformer Help

Hey, I was wondering, how can I get two outputs from a 24v transformer, one for 24v and another for 12v? I've heard of centre-tapping but I'm not sure how to do it, or the transformer in mind is suitable. Thanks for your help.
P.S What does VA stand for? The mentioned transformer states it is a "standard 6VA 24v transformer." It comes from Maplin. Any help will be much appreciated.

If the transformer doesnt have a center tap already you cannot add one.
But you can still get the voltages you need by using voltage regulators, after you add a rectifier of course.

VA stands for Volt Amps, you could loosely think of it as the equivalent of DC watts ( volts x amps) but not exactly the same.

Hey thanks, now I can finally start to understand how to get it right