Subject: Re: Why is the "Group Section" in the Compose a New Message greyed out on my Dri...
Because you are "in a message thread"; i.e., you are viewing another post. When you are viewing another thread, all you can do is to reply this thread.
To post a new message to "this group", click on "All Posts", and you will see a "New Post" link there.
DriveHQ.com has created a few public BBS groups; you can also create your own BBS groups by creating your own content groups. Note your own BBS groups can only be accessed by yourself and your friends in the "Contact Group".