I would start out with a few seconds.....O.K maybe a minute
with you there. Once she goes in willingly give her a treat and lots of praise. Keep doing this and working your way up to a few minutes at a time. It may take a few days (or even longer) Then when you think she feels pretty comfortable with the door shut, then maybe try leaving the room or house for a couple minutes.
Make it extra comfy and maybe put a good stuffed-filled kong to keep her busy. When we leave the house we always keep the radio or TV on for them
Hopefully someone else has some more adivce for you!!