If another section is available, register for it. This may mean re-arranging your timetable. Limited assistance will available through the Faculty of Science office. You will not be contacted if you are moved from the wait-list section into the course. If no other sections are available, contact the department.
Many departments have their own wait-lists.
If the section is restriced, you may not meet the restriction requirements. For example, students with a Year 1 standing cannot register for 200-level Psychology courses. If it's not clear whether a section is restricted or not, please contact either the Faculty of Science office or the Department office to check.