First, give him only a small, quiet room to himself. Have the basics; food, water, litterbox, place to sleep. A bathroom works well, or a bedroom. Important thing is to have available a safe place for him to 'hide' in, and let him hide there until he is comfortable coming out on his own, don't drag him out.
With a small room like that, you can visit him often to bring food or just sit and talk to him, pet him or read a book if he is shy and hiding. As he gets more comfortable, and wants to see what is on the other side of the door, open it and walk out with him for short periods and then return him before he can become frightened of anything. Always leave him wanting 'more'. Eventually, he will grow confident enough to explore the whole house and learn where everything is.
Good luck with the new kitty!