There are 3 ways to add a note to a task:
1. Click on the desired task and go to Task - Task Information – Notes
2. Double click on ID cell associated with the desired task in Gantt Chart, Task Sheet or Tracking Gantt view. 
3. Insert the Notes field inside your table.

To change the duration of a task from days to weeks click on the index of the desired task - Task - Task Information - Duration and type the number of weeks followed by the "Weeks" keyword.

Be careful when deleting multiple tasks as it may affect your schedule and you may lose some information inserted in your project. You can restore them by using the Undo option.

Adding a task is allowed only in Gantt Chart, Tracking Gantt and Task Sheet views. To insert a task select on the View tab one of the above views. In an empty Task Name field, type a task name and press ENTER or press the Down arrow key on your keyboard.​

There are three possible positions where you can insert a task in your project:
1. At the top of the tasks list in the Gantt grid
2. At the bottom of the tasks list in the Gantt grid
3. In the middle, relative to the selected task position: the task is inserted above the selected row.

What does the “Insert Task” functionality do?

The “Insert Task” functionality, as the name describes it, allows you to add a task in project.

What does the “Insert Multiple Tasks” functionality do?

The “Insert multiple tasks” functionality allows you to insert multiple tasks at the same time.

The “Delete multiple tasks” functionality, as the name describes it, allows the possibility of erasing multiple tasks at a time from a project.

There are three available task types: Fixed Units, Fixed Duration and Fixed Work.

The difference between fixed units and fixed duration can be seen when modifying the units and work for a task. For Fixed units tasks, when revising units and work -duration is recalculated. For fixed duration tasks, when revising units - work is recalculated and when revising work-units are recalculated.

To change a task type, double click on the task name in the Gantt Chart, then in the Task Information dialog, go to Advanced tab and in the Task Type group select Fixed Units, Fixed Work or Fixed Duration and then click OK.

If you edit the duration of a fixed work task, nothing happens. Changing scalar work after making an assignment on a task will no longer automatically alter the Assignment Units field.

To see the Task Mode field, use Insert column option under Format menu and select in the Field Name: Task Mode.

You can insert and display this column in views like Gant Chart, Tracking Gant or Task Sheet view. 

Task Mode column displays an icon indicating whether a task, is a manually scheduled task, or an automatically scheduled task.

Lead time is overlap between tasks that have a dependency.

For example, if a task can start when its predecessor is half finished, you can specify a finish-to-start dependency with a lead time for the successor task. You enter lead time as a negative value.

Lag time is a delay between tasks that have a dependency. 

For example, if you need a two-day delay between the finish of one task and the start of another, you can establish a finish-to-start dependency and specify two days of lag time. You enter lag time as a positive value.

To make a manual task a milestone, double-click on the task. In the Task information - Advanced tab, check "Mark task as milestone" - click OK.

A task note is a written message associated with a task.