Here is my guide form my channel, Toslow Gaming. In order to get to Oak Island, you need to give the Peg legged guy 24 peg leg trinkets. He'll then give you clues to the whereabouts of the pieces of the treasure map that locates Kidd's secret treasure. Once you find all, you'll get the option to go to Oak Island. When you get there, you'll have to find the four landmarks. Good luck!