When you add a task from the schedule, it will have the same dates as its’ parent stage but will be coloured a light blue. You cannot create two tasks with the same name under the same stage.
Expand the stage you want to add a task to.
Hover over the stage name and click on the add tasks (+) icon to add a task. A task is indicated by the blue circle icon.
Type the name of the task in the field and either click out of the field to save it. If you press enter, it will add a new task below the current task.
Any changes you make will not be saved, if you leave the task field blank and click out.