I generally buy cider vinegar from my local apple orchard and then use some of it to start a new batch when I get toward the end. But I also found a recipe on line. http://www.candida-cure-recipes.com/apple-cider-vinegar-recipe.html
You could start with the apples or with already pressed cider. I'd use orchard cider though, since it won't have the preservatives usually found in store cider.
Good luck. Hope that helps.