OK, I'll bite. You get a furnace, built out of a suitable refractory material, and you burn lots of fuel, either coke, or natural gas or atomized (that is sprayed from a jet of fluid) fuel oil. Or maybe you can use a Fresnel lens or other large surface area solar collector. Or hey, a laser, of suitable wattage will work too.
I'm guessing you're at home, and have limited metallurgical knowledge, training, and access to the resources I mentioned above. In that case, you can't, because you shouldn't.