A couple of things I found useful when crate training my two youngest was to feed them in it thus allowing them to associate the crate with something pleasant, I also added a blanket, a couple of toys, threaded some of those balls on a rope through the top of the crate and hid some treats in amongst the toys/blanket so they would spend a bit of time in the crate hunting them out. When they got sleepy, I would put them in the crate with a biscuit and left the door open. From here you can start building up to closing the door for increasing lengths of time. I was lucky that mine took to them very easily but some dogs do take longer than others.
