This functionality is built in to Glype.
If your glype theme has the proper <!-- Content Start --> and <!-- Content End --> tags, which looking at your schoolproxy.com, it does have them. Then to replace content, create a php file with the file name you want in the root (public_html) folder, example, proxy-article.php . Now within the proxy-article.php make it look like this :
Notice: There is no closing php tag (?>) in this file.
$content = <<<OUT
<p>Blah Blah Blah. Put your article here.</p>
<p>Continuation of article, blah blah blah.</p>
<p>etc, etc, etc</p>
Then, you can just link to the article from within anywhere in your site, sidebar perhaps, and that new file will replace everything in your theme between the <!-- Content Start --> and <!-- Content End --> tags with the new content.