Provided you are the instructor of record for the course, you can contact your departmental administrator or send email to icon-support@uiowa.edu and request that the TA or other instructor be added. If your ICON course has only one section of students and no more than one section, you can add the TA or another instructor-designer yourself. See the Online Help section Adding Participants.
Important note: If multiple sections have been mapped into one ICON course, special enrollment procedures are required. Please contact the ICON support staff rather than trying to enroll TA's and instructor-designers yourself.