Cannot Modify Header Information

I added the feed generation code to my code on my news page and it's broken the code.

I get this error: "Cannot modify header information - headers already sent by (output started at /home/alexisar/public_html/news.php:7) in /home/alexisar/public_html/news/shownews.php on line 656"

Here's the php code:

<?php
 $phpns['category'] = '0';
 $phpns['template'] = '9';
 $phpns['items_per_page'] = '3';
 $phpns['mode'] = 'rss';

 include("/home/alexisar/public_html/news/shownews.php");
?>

View it here: http://alexisarts.net/news.php