When you click the [Tasks] icon, you can manage all of your tasks, including editing, deleting, etc. The number next to the icon reflects the total number of tasks you are currently being assigned.
When you click [All] under [Open Tasks], you will be able to see the entire task list. [Past] [Today] [This Week] [No dates] tabs will sort your tasks in time sequencial order.
You can switch either the tasks you've assigned or you've been assigned, by clicking the icon on the top part of Tasks page.