You need permission to be able to post in the Events section. The Events section is for official events planned AHEAD of time.
The reason why they need to be planned ahead of time is so that you don't freak out a bunch of people and make them feel obligated to do this. Planning ahead of time gives you a good idea of when a lot of people may be on and allows some leeway for others to drop out and join in.
Without proper planning, things fall apart. Mods and Ops have a job to do, so the last thing we need is a distraction from our duties when people are crying for help all around us while a spontaneous event is taking place.
This is why we stress about planning events ahead of time.