Tame the horse first by mounting it until hearts appear
Hold one of these foods in your hand:
Golden apple
Enchanted golden apple
Golden carrot
Hay bale
Sugar
Wheat
Apple
Bread
Right-click or use the feed button on the horse with the food selected
Use golden apples, golden carrots, hay bales, or sugar to heal horses faster
Use golden apples or golden carrots to help horses enter love mode for breeding
Feed a horse until its health is restored if it is injured
Feed two adult horses golden apples or golden carrots to breed them
Feed a foal sugar, wheat, apple, or bread to make it grow faster