Instructors will often leave feedback on assignments that students can review from the course Gradebook. To do this navigate to the course and click Gradebook at the top of the course:
The list of assignments in the course will show on the next screen. Click the View option at the far right of the assignment you want to look at:
There may be feedback on the side panel that opens up:
Depending on the type of assignment and feedback the instructor provided, when you click that View link, you may get a screen that looks like this. There is feedback on an individual question and overall feedback: