Game loop

1

I am new to AS3 and come from .net background

I can move an image with a mouse and use a class to load the image .
It works.
q1)how do i put this code in a game loop in .fla file as I need to move objects automatically? Do I use a timer or is there something better?
q2) How do I declare an event when the image from the class ClassImg2 has been loaded? I need to know this in the .fla file.
.fla file below
////


var li:ClassImg2= new ClassImg2("ladybug.png",120,120);
addChild(li);

stage.addEventListener(KeyboardEvent.KEY_DOWN,doSomething);

function doSomething(e:KeyboardEvent):void
{
  
  if (e.keyCode==37) //39 is right arrow
  {
  
  trace("left pressed")
  li.moveleft();
  
  }
  
  if (e.keyCode==39) //39 is right arrow
  {
  
  trace("right pressed")
  li.moveright();
  
  }
  
  
}