Hi Frozen,
I'm new to the world of MAC also and love playing with the voice-command mode. I say "MAC launch Safari"...and it does. It can do many voice commands that I haven't tried as of yet.
There are two choices of using the feature once you activate the option. One is to press the "esc" key first to activate the feature. The second, and the one I use, is to have it on all the time. Then you just say the computer name (which you give it) followed by the verbal command. The computer gets confused if there are ambient sounds in the room.
My "MAC" can tell me the time, do some knock-knock jokes, open Safari and iPhoto. You can program it to close applications and many other things as well but I haven't tried those yet.
Have fun,
Carlos Marques