XML parser, how to get to 1 of many elements with the same name.

I have an XML file like this one:

 <rss xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:wfw="http://wellformedweb.org/CommentAPI/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:sy="http://purl.org/rss/1.0/modules/syndication/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/" version="2.0">
 <channel>
 <item>...</item>
 <item>...</item>
 <item>...</item>
 <item>...</item>
 <item>...</item>
 <item>...</item>
 <item>...</item>
 <item>...</item>
 <item>...</item>
 <item>...</item>
 </channel>
 </rss>

How to get to specific in many of them.

Im using System.xml

Thanks.