I've had a look, via doing the search, for allowing members to add other evernts, apart from birthdays, to the calendar, and found this under the FAQ's

To allow member to post Calendar events:
You go to the Forum/Categories permissions and on the line "Calendar", put it to MEM (Member)

I've had a look in my admin panel, and can't find anything in there for the members to add an event

My forum is: http://hobbiesgalore.forumotion.com/index.htm

go into your admin>>>forum>>>choose the forum you want members to be able to post calender events in and click on the permissions button beside the orange cog. scroll down and click advanced options and then you can tick the box for members to be able to add calender events.

Will see how that helps my members,

The only reason I asled is because the forum is on version 3, and I couldn't get people to add an event other than birthdays. It came up on my screen at the bottom about Add event, but when I asked my members if they could add one they said no