ActionScript 2.0 :: Functions In Object Oriented Classes

I'm new to the object oriented stuff and I'm trying to learn how it works. Here's what I've started on - it's led to a few dilemmas. I have one flash file and two .as each with one class. In the timeline of the fla file, it reads:
ActionScript Code:
var FileObject:ScriptFile = new ScriptFile();
function onEnterFrame(){
FileObject.CallInput();
}

Call input is a function in "ScriptFile.as" that calls another function in "Input.as";
ActionScript Code:
class Input{
public function Input(){
} public function keyListener(target:Number):Number{
[Code] .....

In output, when I press Left, it will say -5 over and over again, and I'm trying to add to xpos value but that isn't happening.