If you like to assign grades for a student's participation in the discussion, change it to a graded discussion by clicking on the checkbox This is a graded discussion. The discussion will be treated as an assignment and instructors will be able to assign scores to each student based on the comments they posted.

Discussion can be individual / group discussion. Select the course and the classes you want to add in the discussion. Then choose who will be attending the discussion. Give title and topic. Fill in Discussion settings and set the schedule date before clicking on the Post button.