If you have any notifications, you will see a jewel in the upper right corner of the Activity Tab indicating how many notifications you have.
You will also receive a notification when someone shares files or folders with you. To view your Notifications, in the Tab Navigation Bar, select the Activity Tab.
Notifications are sorted to the top of the Activity list and are identified with an X in the right hand column.
You can view the document being shared with you by clicking its link.
You can dismiss the Notification by clicking the X in the right hand column.