Open the Manage Task Lists page.
See Managing Task Lists.
To copy tasks:
Select a task list, then select Actions, and then select Edit.
To move tasks:
Select a task list, then select Actions, and then select Edit Task List.
Select a task, then select Actions, and then select Edit Tasks.
Select the task that will be a child of another task, then select Actions, and then select Cut.
Select the task that will be the parent task, then select Actions, and then select Paste.
To cut and paste tasks: