He's going to have a lot of anxiety at first, being separated from the mother and his litter mates. Do you have anything with the mother's scent? You can get a toy that simulates a heartbeat. Also, make sure he's had lots of exercise before putting him in the crate, and try to let him enter the crate on his own power, when in a calm state. Those are things that have worked for us with our puppies over the years.