Start to feed your dog their usual meal inside the crate. Simply place their food inside and let them go in to enjoy eating it. Once you’ve done this for a few mealtimes, close the door to a very slightly ajar position when your dog is eating, so they can still exit if they need to.
It might feel different being inside with the door almost closed, so always go at your dog’s pace and if they look worried just go back a stage.
Once they confidently eat their meal inside start to secure the door while they’re eating, and when they’ve finished use the roof opening or slightly open the door to toss a few treats in one at a time, again gradually eking out the time in between, so your dog learns to stay in their crate for longer without their main meal.
Aim to drop a treat in when your dog is calm and quiet, because this is the behaviour we want when they’re in their crate.