Like Avery said desensitizing is super important. Be creative bring a plastic bag, umbrella, loud noises, a dog, ... while training she will realize she does not have to be afraid and it will happen quicker and quicker. If it is to much it always helps to have a very confident horse near by who can take the lead. Also always be confident yourself!
practice desensitizing your horse by exposing him/her to lots of new objects. Remember to take it slow and be confident so the horse thinks its no big deal.
Lungeing ground work. Found out who what why