Oceania Cruise Loyalty Program

I’m trying to figure out some details for the Oceania Cruises Loyalty Program, specifically the benefits for returning customers. I understand they give loyal customers discounts, onboard credits, and priority booking, but I don’t know how to get levels in the program or how to sign up. If anyone has signed up, it would be helpful to explain the process. In case of booking related questions or for quick assistance, it is better to call their support line, +1-888-653-0010 (OTA), for more precise information.