What does it mean to subscribe to the site and how can I do it?
What it means is that the site can notify you through one or more channels, or methods, that information on the site has been added or updated. There are several ways to subscribe to the site. Three common ways to do this are:
Below I’ll explain what they are and how they work, from a users perspective.
Twitter 
What the heck is twitter and why would I want to use it?
Twitter has been called a lot of things and for people that have never used and experienced it they say they don’t like it and it makes no sense… What would you do with it? Why would anyone want to know that I was taking out the garbage or that my BART train was delayed, that I was walking my dog, again, just like I do every morning? Certainly these are the things that you can do, and they might even be some of the things that some people might put up.
With Twitter, you can follow (subscribe to) a feed meaning if someone puts something on their account, it will be made available to you immediately. You can also search for topics like Democrat, Rebublican, 49er’s, Cowboys, Apple, Microsoft whatever you want.
After you chose to “follow” someone or a feed, you can then choose to be notified when that individual posts.
I’ve set up our website to “tweet” whenever a new post is made. I follow the feed and have it alert me via cell phone. Seems sort of goofy since I’m creating 90% of the content… Once you folks get more adventurous, daring, whatever you want to call it, I’ll be alerted to check out the post and can help if you need it. What I do for a friends site.
Lastly, Twitter has the capability of being a two way communication.
RSS Feed 
RSS (Really Simple Syndication) is a standardized web feed format used to publish frequently updated material on the web. The format is based largely on XML (eXtensible Markup Language).
XML is also used by the latest versions of Apple’s iWork, Microsoft Office and OpenOffice.org. The most commonly seen icon for an RSS feed is shown above.
Here is a primer on RSS feeds. [1] Basically, you subscribe to an RSS feed in a feed reader (all major browsers have feed readers incorporated except Chrome and there are numerous standalone feed readers too). When you open your reader, all of the most recent content from each of your feed sources is right their, ready to go.
Some of the settings are set by the publisher and some are set by you, the reader. What this means, for example, is that you can set up a feed from a newspaper so that if you don’t look at it for three days you see only the most recent items OR you could set it up so that all of the news since you last looked at it.
The beauty is that you control what you look at. Once you’ve identified something that you want to go back to periodically, it can be done automatically.
e-mail 
A third, and familiar to most, is e-mail. If you sign up for e-mail subscriptions the site will automatically send you an e-mail on any day that new information has been published. No new stuff and no e-mail is sent. Three articles in one day, still only one e-mail. Fairly painless.
All three of the methods listed are available on the site. I use all three only because I want to verify that you the viewers can get what you want however you want to get it. Try one or try them all.
Just look for the icons that are shown in this article on the site and click to subscribe. Currently they can be found at the top of the far right column.