Event campaigns are an action type that is only available to groups who have been approved for access.
To apply for access, from your group's participate or manage page click the "Event Campaign" button in the "Create A Sponsored Action" sidebar on the right. If your group does not yet have access to event campaigns, you'll be prompted to contact us to apply for access. We'll review your application and let you know when you are approved.
For all of our documentation on event campaigns, click here.