Users can set a due date when creating a new task or by modifying exsiting tasks.
From My Day:
1) Right click and select Edit Task.
2) Change the Due Date and click SAVE.
From Tasks:
1) Double click on the task to pull up the edit menu.
2) Modify the Due Date and click SAVE.
From Calendar:
1) Right click on the task and select Edit Task.
2) Select the Due Date and click SAVE.