What is Brown's motive for going to forest?what results does he expect from his journey? what does he expect the rest of life to be like?

Goodman Brown went to the forest to meet the devil. He deceives his wife and calls it an errand. He wants to flirt with the dark side. He is fascinated with the evil Puritans are so scared of,

"With this excellent resolve for the future, Goodman Brown felt himself justified in making more haste on his present evil purpose. He had taken a dreary road, darkened by all the gloomiest trees of the forest, which barely stood aside to let the narrow path creep through, and closed immediately behind..."

He expects that he can flirt with evil and yet go back to his pious life with his wife. This, speaks to the hypocrisy of Puritans. Much of the others in the town, including Goodman's wife, are flirting with the Devil too.