I (Frederic) will personally leave comments in the essay section of the course. You should be able to receive a notification in your email inbox and from there click on the “permalink” and you will be able to view the feedback and corrections.
You may also be able to access your previous essays in Your Profile. You can check your essays with its corresponding feedback there.
In general, I will correct the error(s) in red and provide an alternative to your sentence in green font. In most cases, your sentence may be grammatically correct but it can sound more natural with the alternative sentence written in the green font.