Once you have registered, you can access the "My Reader" function of the site. From here you can add RSS feeds from your favorite websites to your reader in order to aggregate the feeds into one central location. To add a feed, click on the My Reader tab. Under "My Feeds", right click on the My Feeds folder. You'll see a pop-up menu. Select New Feed from the menu. 
A new menu pops up and displays a place to enter your new feed URL. You'll find the RSS feeds on many websites, either as a link with the text RSS or with the 
symbol. Copy the URL (Right click and copy shortcut in IE) and paste it here. Click Add Feed.
You should now see the feed added to My Feeds folder. (If not click the + sign next to the My Feeds folder to expand the contents.) From here click on a specific feed to display the contents of that feed in the Post window. Article excerpts with links to the articles are shown in the far right window.
You can aggregate as many RSS feeds as you like. You can also add sub-folders to organize your feeds if you are aggregating a lot of feeds.