So you need to make a furnace. Here is how you make it. Get some cobblestone which you just get by mining stone and put it in a circle or a square with nothing in the center, and you have your furnace. Easy peasy. So let's talk about using furnaces. If you pull some iron ore out of the ground, you need a way to turn it into iron, something that you can actually use. So here you need to put your ore or whatever you're going to burn in the top and put something that burns in the bottom. And out pops an iron ingot.
So coal is going to be pretty much your best fuel source. Most common, very easy to pull out of the ground, and you find it a lot in caves and stuff. And it'll take eight pieces of coal to burn 64 units of an item. Now, let's say you don't have any coal. You're in an area where you can't find any, or you're sticking to one area and you've used it all up. You take some wood ... just chop down a tree and burn that, and you can make that into charcoal. And that's pretty good because that'll burn a lot longer than wood will. You see, you can take wooden planks or even some wood, and you can burn wood with other wood. The wood isn't going to last nearly as long as charcoal would or regular coal, you'll see. It burns down a lot faster, but you can make charcoal. And that's going to last a lot longer.
So, as you can see, I put charcoal in here, and now it's lasting a lot longer. So this is a great way to make a renewable source of fuel for your furnaces so you can keep on mining. So, say, it's nighttime and it's getting kind of dark. Another thing that furnaces are good for is making light. So if you've run out of torches, you can drop some wooden planks or branches or whatever into a furnace, and then you can light it up. That way you can make light without any torches. Of course, if you have wood, you can just burn charcoal and make some new torches.
So let's say you're mining and you have a whole bunch of ore you need to get rid of, or you need to make new stuff. You've got your stack of ore right here, and you could, if you want to get done quicker, you could split that up over multiple furnaces. Or if you just want to leave it, you can actually use a lava bucket which is a great resource because that can burn a hundred items instead of 64. So it's going to last a real long time, and that's a great way to keep a furnace burning as long as you need it. So there's the basics of furnaces.