To follow posts in your course discussions, open the post, then move your cursor over the gray star icon in the upper right corner. Click "Follow".
The star icon turns blue to indicate you are now following this post. When you view this post in the discussion navigation pane, it also appears with a "Following" indicator. For more information about the various indicators in the navigation pane, see How to join course discussions.
Show only posts you are following
In the discussion navigation pane, you can lists only the posts that you are following, regardless of the topic that they apply to. To do this, select Posts I'm Following at the top of the topic list.