In Minecraft, the Furnace is used to turn resources into other usable resources. It can be used to cook food, smelt ore into metals, among other things.
To create a Furnace, you’ll first need a Crafting Table and a Pickaxe of some kind.
Use your pickaxe to mine stone and collect eight cubes of Cobblestone. Place the Cobblestone onto the Crafting Table in the pattern shown below to create your Furnace.
Place the Furnace into your hotbar, select it and right click on the ground to place it. It’s usually best placed inside of your home. Once it’s placed, right click it to use it.
You’ll need a heat source to fire the furnace, which is the bottom slot. It won’t use your heat source until you’ve placed something to cook or smelt in the top. Note that it if you put a stack of items into your heat source, it will keep using them up until you remove items from the top slot, or remove the heat source from the bottom slot.
There are a lot of different heat sources, and wood will most likely be your first, so you’ll probably want to create some charcoal by burning wood. Charcoal will last much longer as a heat source than wood will, so it’s much more efficient to create some charcoal than to keep using wood as your heat source.