The task screen has two sections. On the left side, you see the task list and on the right side the filter menu.
The task list shows all the tasks that were assigned. So also the closed ones. By clicking the word 'Task' in the first column, you'll be sent to the task dashboard itself. From left to right the task list shows you when the task was created, who it is assigned to, if that MI user is online, the state of the task, the priority of the task, and the fan who's the owner of the message. By clicking the title of the column you can change the order of the list.
The filter menu offers the option to sort the tasks in four different ways. You can filter on the state of the task (all states, new, in progress, waiting, and close), priority (all priorities, urgent, high, normal, and low), tasks assigned by you, and tasks assigned to you.