Connie, the API documentation is being exposed incrementally over time as the API methods themselves are polished and fully documented.  If you go to https://yourdomain.com/Documentation/api#/topics/overview, it will take you to the documentation page.  The legacy SOAP web services are still available.  Currently, authentication, mailing list, and contact APIs are exposed and available.  Mail APIs should be finalized in the next couple of weeks followed shortly by calendar APIs.