You will need to download and install an RSS reader, or use a web-based service like Bloglines. Then, you copy and paste the URL of the news feed into the viewer's “subscribe” dialogue). Example RSS viewers include:
FeedDemon - http://www.feeddemon.com/feeddemon/ (Windows)
NetNewsWire Lite - http://ranchero.com/netnewswire/ (Mac)
Mozilla Firefox Web Browser (Windows, Mac, Unix)
Firefox has a feature called Live Bookmarks that lets you subscribe to an RSS feed within the browser. For even more flexibility, you can install a Firefox extension called Sage to read and manage RSS feeds.
Bloglines is a free, web-based service for managing news feeds. There is no need to download or install software, and you can access your feeds from any computer connected to the Internet.