Website design along the lines of facebook groups.?

[Mark123456]

I'm interested in starting a website with a similar design to the Facebook groups, except only the admin/webmaster would be allowed to post new posts - guests would only be allowed to comment or "like" a post.

In this respect it is similar to a blog, but the goal here is simplicity in design. Guests would be able to post anonymously, or they will be able to register merely by choosing a username, a password, and an optional display pic. Nothing else: no emails, real names, addresses, etc.

So I was wondering whether there is some blogging software or otherwise that would allow me to create a website with such a design. Please see this pic to better understand what I'm looking for: http://oi51.tinypic.com/2meog1.jpg

[just "JR"]

This is not a complex development, but it will take you time to complete it (about 1 month if you have good experience in server-side scripts and databases).
There are plenty of blog/facebook scripts around: just google them.
LEARN from them and adapt the code to your needs. That will take you probably two months.
You will still have to edit the code using Notepad++ or similar, as hese will be hard to include in the commonly used IDEs such as Dreamweaver...