First of all, read this part of the help section:
http://artdc.org/forum/index.php?action=help;page=post#calendarFirst, you must be logged in!
Then as written in the help section, "You can post an event by selecting Calendar from the main menu followed by Post Event from the calendar screen. What you see now is a Start new topic screen with supplementary fields for the event title, date and target board, which simply add your event to the calendar and create a link back to your post in that board."
As an alternative, after logging in, visit the home page,
www.artdc.org/forum/ and scroll down to the "What's On Tap" mini-calendar and click the numerical date of interest, this should take you to a window that will allow you to fill out information about your event. Be descriptive. Include links if possible. Be sure to include both the Event Title and Subject. The Subject will show in the Events Post, while the Title will show on the Calendar. Please keep the Event Title short!
When posting events, please post only the opening of the event so it shows only once in the calendar. Include the full dates of your event in message body as not to overload the actual calendar.
