Instructors are the authors and copyright owners of their teaching materials (this includes things like lecture notes, PowerPoint slide presentations, assignment instructions and exams). Since a copyright owner has the right to control what can be done with their work, you may not share your instructor's teaching materials outside the course without their permission, including by uploading it to a public website.
There are, however, certain users' rights included in the Copyright Act which allow the copying of a copyright protected work in certain situations. Under fair dealing you may copy an excerpt of a copyright protected work fr purposes including private study, education and research. For example, you could print your instructor's slides to make notes on and study from.
You own the copyright in your own class notes and assignments. You can share these however you like.
Contact the Copyright Office (copy@sfu.ca) with any questions.