Modifying The Xml File

[Connie]

I'm learning parsing the xml tags from the existing data through a template that I created.
Please... explain details of how to read -> modify/delete -> then save the xml file.
And if I be do it through custom templates that I use.

Please, i should be do this in order to create a template for the "Get Simple".
I understand the design, html, css. but less deepen php :-(

I do not understand your question..

templates are not xml, they are php
pages are xml

you must not understand so much, just open the templates which come with the installation in a texteditor locally and try to find out what is defined where
in the wiki you find all template tags explained