XML display question

Ok, sorry for the rather basic question to follow.

I have just started reading up on XML and I have a question concerning displayed XML content on a webpage.

I understand how to relate an XML file to some sort of stylesheet (e.g., CSS) and display the contents as a webpage. I am confused, however, how you can display XML content wrapped in the standard fixtures of a website (e.g., navigation bars, etc.)

The website I am working with is written in PHP and I am trying to incorporate small articles and the like that are in XML. I have read what I can on PHP parsers for XML, but these seem to output XML. I was assuming there was a way to use PHP to turn particular XML tagged data into a PHP variable that I could use within the PHP code. The articles I could locate on this topic don't seem to explain these issues very well.

am I even on the right track?

Ideally, I am looking to display XML content but also heavily modify its style, format, and placement within a larger website.

Well what i do is use XSLT for the formatting of the XML document and then use the build in PHP commands to parse it with the XML and place it where i want in the page, works very well.