Call a fieldtext in stage from a Class

Hello, guys, I can´t figure out this, hopefully somebody can guide me, since all the related topics I could find were pointing in another direction (create a fieldtext in stage from within a Class).

Lets say I already have a dynamic fieldtext in stage, and its instance name is "txt1".

Now, I want to put some text in it from a Class (not the Main Class, but any other one):

package {

    import flash.display.Sprite;

    import flash.display.Stage;

    import flash.text.TextField;

  public class printText extends TextField{

  public function printText () {

  TextField(root).txt1.text = "abc"; // This didn´t work

  this_parent[txt1].text = "abc"; // Neither do this

            }

       }

  }

Any help would be really appreciate it!

Happy hollydays to everyone, thanks in advance!