To get to a customers/prospects Account you will use the search bar at the top of your screen.
You can search by entering the First Name, Last Name, or the Last 4 Digits of the customers Phone Number.
Once in the customers accounts you will see 13 Navigation Tabs, you will want to select the one that says "Tasks".
You will be able to track any tasks associated with the Customer. This includes tasks that have not been Started, ones that are In progress, Completed, Waiting, Deferred, and Past Due.