[F9/AS3] HelloWorld project

[walnoot]

Since there's no AS3 forum and I know a couple of guys around here are already progressing in AS3 I hope you don't bother me asking a total newbie question on this.

Here they give the really first start in AS3, the program that's always your first in every language:the HelloWorld application.

They tell you to make a Greeter.as

package 
{
    public class Greeter 
    {
        public static function sayHello():String 
        {
            var greeting:String = "Hello World!";
            return greeting;
        }
    }
}

and a HelloWorld.fla

var myGreeter:Greeter = new Greeter("Bob");
mainText.text = myGreeter.greeting;

in the HelloWorld.fla you drag a textfield on the stage and give it the instancename:mainText

when I test the movie it says:

ArgumentError: Error #1063: Argument count mismatch on Greeter$iinit(). Expected 0, got 1.
	at Timeline0_f9b48cb254eeb04dbca16453c75a97e/::frame1()

I really want to take the time to intensively study AS3 in the upcoming years but for now I really don't understand what I do wrong, I did this tut three times over to ensure myself I didn't make any typo's.

Thanks in advance,
Wouter