Recent news items are posted there. The most recent ones are at the top, and older ones are lower. Also check the Recent Discussion button in the navigation area on the left side of the site. That will take you to a page that lists all the recent discussion messages. Most recent posts are at the top, older ones are lower down.
Discussion is threaded.
You may post a response to someone else's message. To see a list of every topic that's been begun, check out the List by Topic link. That will show every top-level topic that's been posted since the beginning of the month. As more people join up and introduce themselves, there's more in that thread for you to read. Manila takes care of all the drudgery of what things go where.