To begin crate training, teach the dog just to go in to the crate without closing the door. Toss high value treats in and praise the dog just for going in to get them. Once they are happily doing so, get the dog to go in the crate and feed him/her treats as long as they remain calmly in the crate. Once they are calmly accepting treats, try briefly closing the door. Eventually you can try latching it and feeding treats through the door. With time, you can try latching the door and walking to the other side of the room and back.
With each repetition of the exercise you can leave them in the crate a little longer. Once they can stay in the crate quietly for 1-2 minutes, then try leaving them in the crate for 5-10 minutes while you’re in the room. It’s a good idea to give them a longer lasting treat such as a bully stick or Kong toy. If they are comfortable with being closed in the crate while you’re in the room then you can try leaving them, starting with 30 minutes and gradually increasing the time. Again, when you leave them for long time periods give great, long lasting treats to keep them busy. These steps should not all be attempted in one sitting but should be done over a few days.
Do not try to move to the next step if the dog is not comfortable and calm with the step you’re currently working on. Rushing a dog through the process will create negative associations and make crate training more difficult. Try not to pay attention to the dog or let the dog out of the crate while they are fussing; instead, wait for a calm moment and then let them out.