Go directly to the island from the boat at the port. Make sure you have 10,100 Simoleons remaining. If you are short by a small amount of money, talk to the tourists and make them love you to get more. Go by the bay side until you see a blonde rich girl named Elizabeth. If you make her happy she will ask if you would like to buy a house. Buy the house. The house has a pool, three rooms, a gate, and a big flower bed. She will tell you more about her and become a best friend.