How to edit/update data into an XML file using Flex and Actionscript

Question

I can read an external xml file, please see the code below:
protected function button1_clickHandler(event:MouseEvent):void
var GrowthChartsDataGrid:XML;
var loader:URLLoader = new URLLoader();
var request:URLRequest = new URLRequest("../GrowthChartsDataGrid.xml");
    loader.load(request);
    loader.addEventListener(Event.COMPLETE, onComplete)
function onComplete (event:Event)
     var loader:URLLoader = URLLoader(event.target);
     GrowthChartsDataGrid = new XML(loader.data);
     GrowthChartsDataGrid.GrowthChartGridView += <Month> {txtMonth.text} <Weight> {txtWeight.text} </Weight> </Month>
     texttesting.text = GrowthChartsDataGrid.toString();
I can read an XML file and can add an extra node and can display it in a text filed. But I want to update the XML file contents which will come from the txtMonth and txtWeight text boxes.
Please any suggestions???

Answer 1

First of all thanks for your quick reply .
I actually want to add another node inthe xml file. Files is at a local location and i can read the file and add an extra node (but I cant store this extra node in the actual XML file). But I want to save XML with the extra node.
For exmaple,
my current xml is:
<?xml version="1.0" encoding="utf-8"?>
<GrowthChartGridView>
    <Month> 1
    <Weight>3.5</Weight></Month>
<Month> 2
    <Weight>3.9</Weight></Month>
<Month> 3
    <Weight>4.5</Weight></Month>
</GrowthChartGridView>
and at run time, I can create a new node using the data from two textboxes at button click event.
     GrowthChartsDataGrid.GrowthChartGridView += <Month> {txtMonth.text} <Weight> {txtWeight.text} </Weight> </Month>
Now what I want to do is, I want to add this node back in to my XML. Therefore, the result I am looking for is, my local XML should update like this.
<?xml version="1.0" encoding="utf-8"?>
<GrowthChartGridView>
    <Month> 1
    <Weight>3.5</Weight></Month>
<Month> 2
    <Weight>3.9</Weight></Month>
<Month> 3
    <Weight>4.5</Weight></Month>
<Month> {txtMonth.text} <Weight> {txtWeight.text} </Weight> </Month>  //I can read data from text boxes so its fine but I can not store this in to                                                                                                          my original XML
</GrowthChartGridView>
Thanks