What structure is the syllabus expected to have?

This is completely up to you. An interactive syllabus may have, for instance, one of the following forms:

a syllabus containing as many chapters as there are weeks in the term (one chapter for each week)
a syllabus containing as many chapters as there are topics you want to deal with during the term
multiple syllabi (one for each seminar group)
a syllabus containing multiple chapters – some for lectures, some for seminars
a syllabus containing general course-related information and its chapters with seminar group-specific information

Provided some seminar groups have been created under your course, the application used for creating a new syllabus allows you to select between a lecture (course) syllabus and a seminar group one.