Handle XML with Actionscript

I am quite new when it comes to actionscript. I want to have a next button that will control the text that is pulled in dynamically from an XML file. Here is an example of what I have so far:

XML Code:

<directory>
    <contact>
        <name>Tom</name>
        <address>123 River Rd</address>
        <phone>555-1234</phone>
    </contact>
    <contact>
        <name>Dave</name>
        <text>456 Lake Ln</text>
        <describe>555-4321</describe>
    </contact>
    <contact>
        <name>Steve</name>
        <text>789 Stream St</text>
        <describe>555-5678</describe>
    </contact>
</directory>

Actionscript Code:

function loadXML(loaded) {

if (loaded) {

_root.inventor = this.firstChild.childNodes[0].childNodes[0].firstChild.nodeValue;
_root.comments = this.firstChild.childNodes[0].childNodes[1].firstChild.nodeValue;
_root.describe = this.firstChild.childNodes[0].childNodes[2].firstChild.nodeValue;
describe_txt.text = _root.describe;
name_txt.text = _root.inventor;
comment_txt.text = _root.comments;
} else {
  trace("file not loaded!");
}
}

xmlLoader.addEventListener(Event.COMPLETE, LoadXML);



my_xml = new XML();
my_xml.ignoreWhite = true;
my_xml.onLoad = loadXML;
my_xml.load("data/phonebook.xml");

So when I open the swf it is showing the first contacts information (tom,123 River Rd, 555-1234). I would like to program next and back buttons to change the information displayed (show the next contact information or the previous contact information). For the life of me I can't figure out the actionscript to make this happen. I would appreciate any help I can get. Thanks in advance.

Place two buttons on the main timeline in the frame with this script. Give buttons instance names of 'btnNext' and 'btnPrev'.

Code:

---

stop();

var my_xml = new XML();
my_xml.ignoreWhite = true;
my_xml.onLoad = loadXML;
my_xml.load("phonebook.xml");
var my_num = 0;
var my_total = 0;

btnNext.onPress = doNext;
btnPrev.onPress = doPrev;

function loadXML(loaded) {
        if (loaded) {
                my_xml = my_xml.firstChild;
                my_num = my_total = my_xml.childNodes.length-1;
                doNext();
        } else {
                trace("file not loaded!");
        }
}

function doNext() {
        (++my_num>my_total) ? my_num=0 : null;
        updateFields();
}
function doPrev() {
        (--my_num<0) ? my_num=my_total : null;
        updateFields();
}

function updateFields() {
        name_txt.text = my_xml.childNodes[my_num].childNodes[0].firstChild.nodeValue;
        comment_txt.text = my_xml.childNodes[my_num].childNodes[1].firstChild.nodeValue;
        describe_txt.text = my_xml.childNodes[my_num].childNodes[2].firstChild.nodeValue;
}

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