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If your site were a XOOPS site, it would be easy. You would set up an "admin" user group with the appropriate permission levels. she would log in and go to the admin area of the site and would only see the news, static page, or whatever module she wants to edit. All she would need is the info she wants to add and an internet connection.
If you are looking for answers on your site as is, I can't help you.
-Matt