Need help with flash 8 actionsript using the tween class

Ok, just to be clear - I'm a complete neophyte with programming in general and actionscript specifically.

I have a simple graphic on my stage that I want to have fade in or out with actionscript.  I want to place actionscript in the timeline to control when I want this item to fade in  and when I want it to fade out.   Beyond that I'm clueless as to how to make that happen.

I found the script I've pasted below, which seems to do what I'm looking for - but it is controlled by a mouse rollover - not a specific timeline occurrence.

I'm hoping someone could help me to change this script (and tell me how to use it on the timeline) so that I can have my graphic fade in and out when I need it.

Thanks a million, in advance, for any and all help with this.

Here is the script I found:
//first import the class libraries
import mx.transitions.Tween;
import mx.transitions.easing.Regular;

//now initialize the tween object
myButton.alphaTween= new Tween(myButton, "_alpha", Regular.easeOut, 50, 50, .3, true);

function onRollOutHandler(){
    this.alphaTween.continueTo(50);
}

function onRollOverHandler(){
    this.alphaTween.continueTo(100);
}

myButton.onRollOver = onRollOverHandler;
myButton.onRollOut = onRollOutHandler;