You can set Tasks to record the date that you completed the task, and you can select to show or hide completed tasks. Completed tasks remain in the memory of your phone until you purge them.
You can display your tasks in your calendar. See “Customizing display options for your calendar” on page 109 details.
Open the menus to access other features such as importing phone numbers into the Tasks list.
Tasks
You can use Tasks as a reminder of tasks you need to complete and to keep a record of complete tasks.
Adding a task
1.Go to Applications 
and select Tasks 
.
2.Select New to create a new task
3.Enter a description of the task. The text can be longer than one line.