Stairs can be scary for dogs who are not use to them the best thing is not to drag her to the stairs. Try sitting on them and calling her up stair by stair, changing the look of the stairs can help her get over the fear. Only do one at time and that should really help.
Any time you drag a dog toward something they are scared of you can set the fear in s instead try and get them to go to it by having them follow you.
This is normal and you can work her out of it