how to create a marquee selection and then write some texts inside

This is another example to fit the text to the selection....

It will create two documents...

createExample("Example Text");
createExample("Example Text and this fits too");
function createExample(text){
var startRulerUnits = app.preferences.rulerUnits;
app.preferences.rulerUnits = Units.PIXELS;
var FontName = "Georgia"; 
var FontSize = 4;
var black = new SolidColor(); 
black.rgb.hexValue = '000000'; 
//create a new document  @ 72 PPI
app.documents.add(600,400,72,"Justification Example");
var SB = new Array();
SB[0] = 20; //Left
SB[1] = 20; //Top
SB[2] = 300; //Right
SB[3] = 200; //Bottom
//make a selection
activeDocument.selection.select([[SB[0],SB[1]], [SB[2],SB[1]], [SB[2],SB[3]], [SB[0], SB[3]]], SelectionType.REPLACE, 0, false);
//Stroke selection so you can see the results
activeDocument.selection.stroke (black, 1, StrokeLocation.INSIDE, ColorBlendMode.NORMAL, 100, false);
//new text layer
var newTextLayer = activeDocument.artLayers.add(); 
newTextLayer.kind = LayerKind.TEXT; 
newTextLayer.textItem.kind = TextType.POINTTEXT;
newTextLayer.textItem.color = black; 
newTextLayer.textItem.font = FontName;
newTextLayer.textItem.size = FontSize; 
newTextLayer.textItem.contents = text;
var LB = activeDocument.activeLayer.bounds; 
//create text 6 pixels less than width of selection
var selWidth = (SB[2]-SB[0]) - 6; //create text 
var LWidth = Math.abs(LB[2].value) - Math.abs(LB[0].value);    
var percentageWidth = ((selWidth/LWidth)* 100);
activeDocument.activeLayer.resize(percentageWidth,percentageWidth,AnchorPosition.MIDDLECENTER);
var X = SB[0] + 3;  //Three pixels to the right of the marquee selection
var Y = ((SB[3]-SB[1])/2) + (SB[0]+ (LB[3]-LB[1])/2); //Find the middle of the marquee selection and add the pixels top of selection to top of document.
//Position text
newTextLayer.textItem.position = Array(X, Y); 
//Convert the document to 300 PPI
activeDocument.resizeImage(undefined, undefined, 300, ResampleMethod.NONE);
app.preferences.rulerUnits = startRulerUnits;
}