When she moves give her a pat and a treat if she stops don't tempt her with food but wait until she's moving to reward her.
Also, don't forget to reward her with a pat or scratch when she does what you want!
If you can't get her to walk forward, try clucking first. If that doesn't work, step towards your horse's hind end. If she still refuses to walk forward, take the end of the rope and gently swing it at her hind end. Don't hit her hard, just enough to encourage her to walk on. Hope this helps :)
With all my horses I move back by their shoulder and encourage them forward and reassuring them
Hope this helps