It can be done, but it might confuse you a bit. The easiest way is to use something like WordPress, which has a comments feature built in, but that would mean rebuilding your site from scratch. There are some other services/scripts that enable you to add a commenting facility to your site, such as
I really don't want to redo my website, bad as it is. Just don't have the gumption to start over again... Any other suggestions would be appreciated. I want to be able to post an update, and then allow people to comment.
I really don't want to redo my website, bad as it is. ... I want to be able to post an update, and then allow people to comment.
Most of the links I posted above provide options that are just added to your site, rather than involving a rebuild. But this is somewhat complex stuff, so it's never going to be as simple as HTML/CSS. As zeeb44 said, Disqus is probably the easiest option.
If your host supports PHP it should be easy to create a page that will be the destination of a form post.
You build a small form on your site and when it is submitted it calls a simple PHP page that can generate an email message to you with the comment.
Disqus is a popular one. But adding a Facebook API for the comment thread would be easy. Go to the developers area of Facebook and grab the code for it. Then if you are signed into Facebook it lets you comment on it.
I can definitely recommend Disqus as a great comment system solution. It's often so painful to roll out your own, and quite frankly Disqus probably have more experience in rolling them out collectively than any of us here do.