RSS (Realy Simple Syndication) is a format for syndicating news and website updates. To subscribe to an RSS feed, you will need an RSS reader, which can be either web-based or an application that you download.
The Constellation-X News feed will contain the same announcements that appear on the Constellation-X front page. To subscribe, find the place in your chosen RSS application to add new feeds, which will often look like a URL box from a web browser. Then cut and past the following URL into the input box:
http://constellation.gsfc.nasa.gov/rss/feed.rssFinally click on the "add" or "subscribe" button (depending on the application). When a new Constellation-X announcement is made, it will show up in your news reader.