Put a knot in your rope so the hondo will hit it and keep the loop from getting any smaller then about a foot in diameter. Loop over the young horses head and apply NO pressure. Let the colt carry the loop and do not pull on it. When he stops let him feel a tiny bit of pressure from the loop until he makes a slight movement in your direction and release and reward him. He will learn to lead with slack in the rope. If you take all the slack out of the rope you are pulling to hard.