To see these options click the File tab , click Options, and then click Task Info.
Select the days of the week to use as workdays.
Click Add date to add a holiday that will not be counted as a workday.
To remove a holiday, select it in the list and then click Remove date.
Enter the number of hours in each workday.
These settings are used on all maps that you create.
To define different settings for individual maps, use the Task Info Calendar & Display option.
Select Show Effort to display this field in the Task Info pane. This setting allows you to set an effort time that is different than the task duration.