Just what are RSS feeds? What do they do? Why should you be interested?
Wikipedia defines RSS as:
RSS (Really Simple Syndication) is a family of Web feed formats used to publish frequently updated content including, but not limited to, blog entries, news headlines, and podcasts. An RSS document (which is called a “feed” or “web feed”  or “channel”) contains either a summary of content from an associated web site or the full text. RSS makes it possible for people to keep up with their favorite web sites in an automated manner that can be piped into special programs or filtered displays.
So, RSS feeds are a way to have new web content automatically sent to you. Web content means any site or blog that you have an interest that allows it’s content to be distributed in this way.
To subscribe to Google Reader just open your browser and search for “Google Reader.” Once you’re there just follow the sign-up instructions. After completing that you are ready to add feeds that meet your personal taste.
There are probably millions of websites and blogs available. Google Reader has some nice packages which you can pick from. Don’t be confused by this, you can add any site you wish weather Google knows about it or not. As long as the site provides the feed you can subscribe to it.