How to use classes of packages in flex mx:Script/ or mxml/

Question

Hi.I am just learning Flex using Flex Builder 3 facing one problem,
Suppose I declare one package with name alert.as
package
import mx.controls.Alert;
public class alert
public function alertBtn()
Alert("Hello btn 1");
Now in want to use the function in mxml that I declared in a package.
<mx:Button label="btn1" click="alertBtn();"  />
I have few questions
1)How to Import the class alert.as in <mx:Script> and where should i store the file alert.as in the directory folder of flex?
2)How to call the function alertBtn() when btn1 is clicked.
Thanks so much!
Regards
Ankur

Answer 1

Hi Greg.I think I was not able to clear my problem properly.Let me try this time again.
What I wanted to do was that in the below written code I have the full access of the id=panel1 in the  script tag .This works properly.
<?xml version="1.0"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">
<mx:Script><![CDATA[
import flash.display.Sprite;
import mx.core.UIComponent;
private function addChildToPanel():void {
var circle:Sprite = new Sprite();
circle.graphics.beginFill(0xFFCC00);
circle.graphics.drawCircle(0, 0, 20);
var c:UIComponent = new UIComponent();
c.addChild(circle);
panel1.addChild(c);
]]></mx:Script>
<mx:Panel id="panel1" height="100" width="100"/>
<mx:Button id="myButton" label="Click Me" click="addChildToPanel();"/>
</mx:Application>
This above functionality when I tried to do using class Outside the code ,its not working !
Here is with the package:-
But suppose I make One package 
package
import flash.display.Sprite;
import mx.core.UIComponent;
class getPanel extends Sprite
public function addChildToPanel():void {
var circle:Sprite = new Sprite();
circle.graphics.beginFill(0xFFCC00);
circle.graphics.drawCircle(0, 0, 20);
var c:UIComponent = new UIComponent();
c.addChild(circle);
panel1.addChild(c);
          }//class
                    }//package
Now in MXML
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">
<mx:Script><![CDATA[
import getPanel;
]]></mx:Script>
<mx:Panel id="panel1" height="100" width="100"/>
<mx:Button id="myButton" label="Click Me" click="getPanel.addChildToPanel();"/>
</mx:Application>
So My problem is that this code doesnt do anything.
Neither the addChild function is working in it ,Nor the Panel1 is accessible here.
Can u pls help me here.
Thanks
Ankur