ActionScript 2.0 :: Changing The Font Type?

how to make this:

Code:
format = new TextFormat();
format.bold = true;
tfield.setTextFormat(format);

into something like this:

Code:
var col = new Color(this.background);
col.setRGB(0xf4faff);

I'm no AS expert but i think the first example changes the font from outside of the object and the second example from inside the text object.how to make the "this.background" in the second example into "this.whatever points to the font".