Basic information-gathering in this post.
- Where is the Community Bulletin?
- Is there a bigger board than what is floating on the right-hand side of the screen?
- How do you put a post/thread there?
This MSO post explains the community bulletin. Below refers to how the entries are populated:
Moderators and select Stack Exchange employees can add new events from the Mod Links menu, giving each entry a title and beginning and ending date & time. Each entry must be linked to a Stack Exchange property (a Stack Exchange main site or meta post, Blog Overflow blog post, or a post on the main Stack Exchange blog).
If no entries have been manually submitted to be displayed, the Community Bulletin will be populated with featured and active meta posts.