Nick Carraway was born in a big city in the Middle West. When he came back from the War, he decided to head East. He decided to go East because Middle West was dull and he could settle down there. His plan was learn the bond business. He planned to stay for several years in New York but he just stayed one summer in the end.
Nick found a house in East Egg, 20 miles away to New York. That house was between two big house. One of them house it was Gatsby's house, who didn't know yet.
The Great Gatsby - 1 - Tom and Daisy
Daisy knew Nick moved to East, then she phoned to Nick and said they were neighbour and she invited his to a visit. Daisy is Nick's cousin.
Nick didn't believe them, Daisy and Tom, had really settle down because they were too rich and too restless.
They were ateing when the phone rang Miss Baker thought who was on the end of line was Tom's other woman, mistress.
Daisy told Nick that she had a daughter but Nick didn't believe her. (I don't know what reasons she said about this, I could find on the book)
Why Nick knew Miss Jordan Baker? because she had behaved badly in a golf match, he read on newspaper.
When Nick got back home he saw I man stood and he thought that man was Gatsby. Nick didn't call him because He thought Gatsby would like to be alone. That man was stretched his arm to sea. And there were a green light other side of the bay.