The concept of ombudspersons is that students may wish to raise issues or give feedback about the course that they don't feel comfortable confronting the Instructor with directly. Perhaps they already tried posting in the discussion forum, but considered the response unsatisfactory. In that case, they can turn to one of the students who has volunteered for this role as a go-between. Ombuddies can e-mail/talk with the Instructor on a private basis. They can also bring written summaries of feedback to the Instructor, in which case a response will be provided to the entire class.
Look for these students in class, or e-mail them with any concerns: