You want to programmatically position form elements.
Set the _x and _y properties of each element.
Components are derived from movie clips, so they support the basic movie clip properties and methods, including the _x and _y properties. You can set the _x and _y properties of any component to position it on stage, just as you would with a movie clip:
myComponentInstance._x = 90; myComponentInstance._y = 180;
For more complex positioning, see Recipe 11.8 and Recipe 11.22