I broke my iphone and need help backing it up

I broke my iphone 5c a few weeks ago and there was no fixing it so i ordered a new one when i got it in today and i tried to plug the old one in and back it up on itunes so i would not lose all of my data but it keeps saying i need to enter the passcode on my iphone first but i dont have a screen or anything on the phone so how can i get into the phone to back it up?