Help with center

I’m trying to make a movie-clip symbol rotate with Action Script.

It uses the top-left corner as center of rotation (cross hairs) - how do i change this? I want it to rotate around its center.

When i make the same object rotate using a motion-tween, it rotates around its center, the round thingy. And i can drag its center to whereever i want it.

I’m confused, can somebody help me?

thanks