It all depends!
If you have a single date and time that you can attach to an event, the Cerkl team suggests that you use the Event feature, which allows you to attach a registration URL, location, and start and end times to a post.
After appearing first as a Story in the body of your newsletter, Events will filter to the Upcoming Events section toward the bottom of your newsletter. A maximum of five Events will live here at a time. Also, always remember that only events 30 days in advance will pull into your newsletter!