iTunes RSS tags

Hi, I tried adding the itunes tags to my rss2.php, however I ‘m not sure how to write that, if i simply add the tags into the php file, i get this parsing error

I get this error message:
XML Parsing Error: prefix not bound to a namespace
Location: http://www1.rosavientospodcast.com/podcast/?feed=rss2
Line Number 10, Column 1:<itunes:category text=”International”>
^

Thanks.