you have a 15 minute window of time in which to edit your post. after that, the option closes.
if you have something that needs to be changed, you can use the report button to notify those of us on staff.
click that button, and in the report box, just say what you would like changed. which ever one of us sees it will get on it and let you know when the change has been made.
now if you have something like an even that has a constantly changing participant list, etc, and you want the first post in that thread to update as the even, etc gets closer, we can enable it so that who ever started the thread can edit that one post with out having to go through the staff.