A blacksmith is someone who makes things out of metal, particularly iron, for a living. Blacksmiths use tools like a forge, hammer and anvil. Blacksmiths make items like tools, weapons and furniture from iron. Someone who makes horseshoes is called a farrier, not a blacksmith.
A myth is a story that doesn't have a basis in reality, but that many people think is true. A good example of a myth is that you can catch a cold by going outside in cold weather.