updating preexisting XML file

[siege]

I have the following XML file that I would love to be able to setup a simple PHP interface that could:
1. manipulate the data
2. add or delete a 'menu' element

I'm so new at PHP that I don't even know where to start. the only two things I know how to do is prepare the HTML file for the layout and ready it for PHP insertion and obviously write my own XML manually (i know thats really easy). Could someone point me in the direction on how i could get started on this?

<?xml version="1.0" encoding="iso-8859-1" ?>
<navigation name="mensShirts">
<menu itemName="YO!" itemNumber = "SU06M-001" itemAmount = "22.00"/>
<menu itemName="Dunkaholic" itemNumber = "SU06M-002" itemAmount = "27.00"/>
</navigation>

[NogDog]

If you're using PHP 5, take a look at the SimpleXML functions.

[siege]

I have PHP Version 4.4.1, I wish I could change it to 5 but I dont have that control. Is there another place to look?