You will need to have administrator privileges in order to post a new bulletin. Just click the ‘bulletin’ icon at the top of your feed:

You can then give your bulletin a title and description. Like ideas, descriptions are character limited and these are controlled via the main global character limit in settings.

You can add optional attachments and files to enrich your bulletin (maximum file size of 10mb per attachment), in addition to adding categories and tags, just like on ideas. Categories are controlled at a global level in the settings section.

You also have the option to pin your bulletin which keeps the bulletin at the top of the feed so all users can see it.