As a manager or message board moderator, to view the moderation Queue, navigate to Intranet and then Moderation Queue.

From here, you will be able to see all posts and comments ready to be reviewed for the message board. In this case we have 1 post ready to be reviewed.
If you press reject, a pop up will come up asking you to add a reason why to let the agent know what to fix (you can choose from a list of previous fail reasons or create a new one). If you press approve it will be added to the message board.

This is what a comment review looks like. Non-greyed out comment is the one that is being review but it shows other comments for context.