He won't like it at first but its the best way when mine are that small I put them in a small tub with a lid with air holes and a little bit of warm water for about 20mins then put them back in there home and leave them alone over night and by morning they have shed
Pop a damp flannel over the top of his warm hide - the raised humidity may mean he'll be able to sort himself out. You could also move the water dish over to the warm side as well.
It's always worrying when you are new to snakes and things don't go perfectly - and don't worry! If he has to wait until after he's digested for you to then help him it won't do him any harm :) As SBB said, use a damp flannel or towel and let him run through it in your hands - if you make it fairly tight you'll feel him pushing himself against you to get the shed off - don't pull it yourself as you could hurt him, but you could just hold the shed which is coming off and then let him pull himself through :) I had to help Corno with her first 3 sheds, but she then seemed to just get the hang of it herself and has been fine since :)