this is what i do with my one year old :

i walk him up and down the drive way with parked cars ,

then i get him into a field and take a car in there and get him to walk about  am meter away from the the car ( when the car is moving )

then when he is confedent enough take him on a road but not a main road just a little country road and just walk him up and down and then take him on a road that has more cars xxx

eventully they will get used to cars then you could start to ride him on the roads

hiyyaa

i would say more or less the same as every 1 else but with my horse i started off with quieter roads and the worked my way up to big 1s when he was more confident best of luck :)x

Walk him in hand  down a little country road to begin with, do this for about a week and then walk him down a slightly busier road, do this until he relaxes, then ride him down a country road with someone walking with you. When he /she feels relaxed do it with another horse along with you. Gradully so it by yourself. Hope this helps!