What does Gatsby tell Nick about his past?

In F. Scott Fitzgerald's novel "The Great Gatsby," Jay Gatsby tells Nick Carraway that he met and fell in love with Daisy Buchanan and that he was unable to take care of her, even though he pretended that he could. Gatsby went off to war and then on to Oxford and would not or could not go home, even though Daisy wanted him home.

Daisy was under pressure to marry well and because Gatsby was gone, she married Tom. Gatsby does return to the United States to try and find her, but she is away on her honeymoon. He feels that he should have tried harder to find her.