View Single Post
To add a project-wide vacation/holiday, go to the Calendar View (third button from the left in the toolbar) and with NO resources selected, click on "Extras & Off Hours". You'll be able to select the week of the year that you'd like to modify. To add off-hours, hold down the shift key and drag.

To add a vacation/holiday for a specific person you will need to select their name from the list of resources first, then click on "Extras & Off Hours".