Whenever someone leaves comments or feedback on a portfolio you have shared in a community you will recieve a notice next to your username in the upper right corner. The number of comments that have been left will appear next to your name.
You can read what comments have been made by clicking on the username in the top right corner and then clicking on 'Feedback' in the dropdown.
You will then be able to manage your feedback from this screen. This screen allows you to mark the feedback as 'read' or remove them from your inbox.