Here at the OU there are a few student blogs which have a first entry along the following lines:
Cool, I have a blog. This is my first go at a blog. Is anyone actually reading my blog? What is a blog?
So here's a quick, 350 word, intro for first time OU bloggers.
Part I What is a Blog?
What is it?
A blog is a collection of articles, called posts, catalogued with tags - words which relates to an article. An article can - and usually does - have many tags. The same tag can - and should - be applied to multiple posts.
What do I write about?
A post can be about growing beards, hoeing allotments, racing bats, eating salt, tuning cars, tuning forks, packing bags or going nuts. If you can spell it, blog about it.
What are comments?
Readers of posts can leave public comments. Though conversations do naturally occur in these comments I personally think some off topic conversations detract from a blog's/post's impact. We have forums and emails for natter.
What about RSS? 
Readers can be alerted to new posts by subscribing to a blog. This is done via RSS. Find a blog you like. Click the RSS button and be taken to the RSS page. This - most likely text-only - web page is a version of the blog which RSS systems can read. Copy the URL address for this web page and then add it as a new RSS feed to your reader of choice. I use Outlook or Thunderbird but there are tons of other clients.
Adding a RSS feed in Thunderbird:
Adding a RSS feed in Outlook:
Part II How do I keep track of reader's comments?
You will note your blog has two RSS feeds. You lucky devil. The first one is for the blog - for punters - and the second is for the comments. Just subscribe to this 'comments' feed and, like any normal feed, you will get alerts for every new entry.
Part III Is anyone reading my blog?
The way I keep tabs on the traffic is via Google's Feedburner. It is a wonderful application which 'plugs into' any blog. So plug it into yours. It keeps counts of views per post, your subscribers and tons more good stuff. Just go to http://feedburner.google.com and follow the instructions. All you really have to do is paste your RSS address.