Flash 9 / AS3 - calling MovieClips on Stage?

I’ve just downloaded Flash 9 Public Alpha and I’m trying some new stuff. I would like to change the scale of a MovieClip instance that I’ve physically created and dragged onto Stage but the compiler doesn’t recognize the mc instance…

Do I need to do something beyond just referencing the clip? :
myMovieClip._yscale = 10;

Brrr, I have a haunting feeling that AS3 will be too intimidating for me to even begin to try learning, I can’t really grasp AS2 yet…