The professor's feedback is an imperative part of your grades. Checking what the professor wants to improve is important to get a better grade. In order to see their feedback, you first need to:
Once you find your course, you'll see the home page. Click the "My Grades" tab:
Important note: Not all professors leave feedback. Sometimes you won't see the conversation icon beside your grade, that's not a bug or a problem, it's just the way each professor works.