ActionScript 3.0 Tutorials

Functions
Functions enable ActionScript to reuse certain pieces of code over and over. You can define some set of action within a function and then call that function whenever you need the code to run.

When building a function you start the line of code with the word function then the name of the function (basically whatever you want), a pair of parentheses and curly braces. What you want the function to do is contianed inside the curly braces.
To call the function you simple need to call it by name, such as aName().

Construct a function
Click on the first key frame on the time line layer called actions and press F9 to open the actions panel.

then add the following code:

function textArea(){
var myText:TextField = new TextField();
myText.text = "F2 Training";
this.addChild(myText);
};
textArea();

function textArea() creates a new function called textArea. var myText creates a new variable called myText, :TextField is data typing which tells flash and programs what type of data will be contained within the variable you just created.
= new TextField(); defines the variable myText as having the value of new TextField(); The next line of code myText.text = "F2 Training". Is telling Flash that the variable myText has a .text property and that it's value is "F2 Training". This is basically the same as drawing a text field on the stage, naming it myText and then typing F2 Training inside that text field. The differance is that this text field is dynamically controlled and can be called on whenever it may be needed. The last line this.addChild(myText); simple adds the new text field myText to the stage and then places the value inside that text field.