Can someone please explain how the three teams from North America are selected please?

So, I currently understand that the North American LCS is split into two "splits": summer and spring. I also understand that the 1st place team in the Summer Split automatically goes to worlds, but I heard earlier this year that a points system was introduced. For example, winning the Spring split was something like 60 points. So, how are the 2nd and 3rd place teams selected from North America and what are regional qualifiers? If someone could please break this all down for me that would be much appreciated. No idea where the points play in, except for that Riot's source stated "LCS teams will receive championship points based on their performance in the LCS playoffs each split. The points will be used to determine seeding for the World Championship and Regional Qualifiers for North America and Europe." But how could it determine seeding for worlds if the first place team from the North American summer split automatically make it to worlds and then the other teams enter the gauntlet???