These are always promoted to the group homepage, which is sorted by newest first. They will send out an email to everybody in the group who wishes to receive them, so try to make them meaningful. Users may post comments, which are also sent out as an emails to the group.

Members may post a new group blog entry simply by going to the group homepage. There will be a link to "Add a new group blog entry" between the group's welcome message/mission statement and the previous blog entries.

The form's generally pretty easy to figure out, the only two things worth mentioning here is

1. The "Teaser" field, which is where you put what will be in the email sent out and what will appear on your group homepage. If you don't select one it'll select one for you from the first few lines of your post.
2. The "Groups" section, which will be collapsed. If you don't touch that part at all, it will post your blog entry in your group and have it be public. If you click it you'll be able to post to whatever other groups you're a member of and optionally make it private, meaning visible to only the group(s) it's posted in.