This article explains how to use My Work. The My Work feature is designed for Team Members, as a single page to view & update all work assignments. The Plan Owner will see the updated values when they look at the plan schedule and elsewhere (reports, etc.)
Select the check box to mark an item as complete. The field values will get a line through them. Status will update to Completed and % Done will update to 100%.
Update an Item In-Line
Update any field in line that's editable, such as % Done, Status, etc.