New to AS3: how to refer to dynamically created children?

Part one:

// Function to add the interface.
function addinterface():void {
    // Display library object.
    this.addChild (new interface_bars);
}

[..]

addinterface();

Part two:

interface_bars.hit1.addEventListener (MouseEvent.ROLL_OVER, trcseg(1));

Now I can display the interface_bars object fine, but say there are objects inside it that I want to assign events. (There are. I’m just being hypothetical.)

I don’t know if the dynamically created child (from the interface_bars class) has an instance name, or if it does what the name is. And, clearly, the second snippet of code won’t work because interface_bars is a class. (hit1 is the instance name of an object within the class.) trcseg(), by the way, just traces the argument.

Any help for someone who’s only started learning AS3 in the last few hours? Thanks!

(PS. AS3 is pretty cool. It’s so much better structured than previous Flash/AS engines. It’ll just take a little while to get used to it…)