I assume she is halter broke? If so, we started out with one person in the saddle the other with the lead rope. The person in the saddle gives the cues. Hands forward, kiss, leg, etc while the other person would give the halter cue from the ground as the last cue. You need to up the insistence of the cue until you get forward movement then release all pressure. Does that make sense?
Each thing is a sort of pressure.
Hands forward if no response then kiss, if still no response then leg pressure, if still no response slap with a lead rope or whip (I start off tapping my leg) if still no response person on ground gives cue to walk out. When the response is achieved again remove all pressure.
If your up to it, have the person at the end of the lead rope drive with whatever you have used in the halter training (lunge whip end of lead rope etc.)
The bottom line is pressure, pressure, pressure until the horse gives the proper response. The release of the pressure is the reward for doing the right thing.
Hope that helps a little