You can always find details on the tournament structure via the infographics found in the "Promotions" link within the navigation bar at the top of the site. You can also access this page directly by clicking the link below or pasting it into your browser's address bar: 
https://sni.ps/FeaturedTourneys
Below are the details for the current tournament series' featured on this page:
Main Event Mania Series (see rules at https://play.nlop.com/content/_content/vip/rules.html ):
