Event from existing thread

AoEZone Calendar

AoEZone calendar can be used to submit Age Of Empires related events. You can freely submit events but they have to be approved by a moderator before they appears in the calendar.

Event from existing thread

You can create a calendar-event after you have created your thread. Just create your thread as ususal in preferred forum.
After the thread are created enter the thread and activate the thread-menu and select "Add calendar event". You will then get the usual calendar for to fill out. Adding events this way let you post threads in other forums than Event-Calendar and still be able to add the thread to the event calendar.

More infor about the event-calendar can be found here.