AS2 - AS3:: adding MC's to a 'container' MC

Hi Im new to AS3 from AS2… and am learning the basics…

I know now how to add a load of MCs from the library to the stage.

Do I still use MovieClips!!!?
I have a simple question::: How do I populate a ‘container’ MC with ‘instances’ from the library? I know i am using AS2 lingo, but it is to make my point clear. I understand that you gotta get into classes with AS3 …

Before in AS2 I would …


in AS3::: and cutting to the chase without referencing packages, importing etc … just straigth to the particular part of the code::

var cont:MovieClip = new MovieClip();    
for (var i:int = 0; i < 10; i++)
   var newMC:myOBJ = new myOBJ();
   newMC.x = Math.random()*300;   

Is that right? ! Thanks;(