Help with xml

Hope someone can help me out here.
What I am trying to do is like create a blog via loading the text from an xml file. In my main page it will only display few lines from each entry of the blog. After those few lines theres a hyperlink which says “read more”. So when the user clicks on this, I want the whole entry to come up in a pop up window. The trouble I am having is reading which entry the user has clicked on so that the right one is fully displayed on a pop up window. Thanks again for your help.