If you enabled the Discussion Board function in groups, you will need to add a forum to the discussion. Students only have the rights to add threads to a forum, they cannot create forums.
To add a forum you need to log in to Blackboard and navigate to your course. Once your course is open, click on the Communication button.
In the Communication screen, click on Groups.
Click on the link for the group that needs to have a forum added to its Discussion Board.
Once you are in the group, click on the Group Discussion Board link.
To create a forum in the Discussion, click on the Create Forum button.
You will need to give the forum a name and description.
Set the Forum Availability.
You will also need to select the settings for the group. Because this is a small group, and they should be working together, there shouldn't be any reason to allow users to post anonymously. You can also select if the author of a post will be able to edit or remove their own posts. You can also select if users can attach files to posts.
To complete this action, click on the Submit button.
Your forum has been added to the group.