At UiO, many lecturers use Canvas. Canvas is UiO's learning management system where the lecturer keeps in touch with the students and publishes work requirements, assignments and other materials to students. You, as a student, can also submit assignments and collaborate with other students.
The use of Canvas integrated with the course or courses you are registered for, and how Canvas is used in your education is up to each individual lecturer. If you do not find your subject in Canvas, it is possible that the lecturer does not use Canvas or that the course has not been made ready yet.
It is common for lecturers to tell you how they set up the education and how and if they plan to use Canvas.