OK, on one hand, it is pretty straight-forward that you are going to post your feedback through your course management system. But that is not as simple as it sounds. For example, in BB, you could post feedback on a rubric; it could be directly on a submitted paper; it could be in the "feedback to learner" box; or it could even be through email. The important thing is that your students understand where your comments are going to be, and maybe even more importantly, know how to find those comments. For example, in our courses a lot of students are unable to find the rubrics.
You should also consider sending out to the entire class some general feedback on an assignment; that can be done either before the assignment due date (so students have some ideas of what to, or what not to, do on the assignment) or you can send out some general notes after an assignment has been graded.