Your first night in Minecraft, then the first 10 hours
With no coal, smelt a log in the Furnace to get Charcoal:

Coal is the everyday fuel of the game: one piece keeps a furnace running for 80 seconds, enough to smelt eight items. It comes from coal ore, one of the most common ores, and is just as needed for torches.
It is made with the Crafting Table from Block of Coal (other recipes also exist). As fuel it burns for 80 seconds in a Furnace, enough to smelt 8 items.
A coal on top of a stick gives four Torches, the light source that keeps monsters from spawning in your base and tunnels. Coal also goes into the Campfire, into Fire Charges with gunpowder and blaze powder, and into soul and copper torches.
In a Furnace, Blast Furnace or Smoker, coal burns for 80 seconds; the faster blast furnace and smoker get through it twice as quickly. Nine coal make a Block of Coal that burns a bit longer than the nine pieces separately, handy for big smelting jobs. A Minecart with Furnace also runs on coal.
Charcoal, made by smelting logs, does almost all of the same jobs if you have no coal ore at hand. Novice armorers, toolsmiths, weaponsmiths and fishermen buy coal for emeralds.
Block of Coal → 9 × Coal
Coal Ore → Coal
Deepslate Coal Ore → Coal
Coal Ore → Coal
Deepslate Coal Ore → Coal
// Slots with several items cycle through every accepted option.
With no coal, smelt a log in the Furnace to get Charcoal:
emeralds for Coal and fish, enchanted Fishing Rods
Underground, Coal Ore gets more common the higher you go, up to Y 96 inside hills; in caves under flat land, which stop around sea level, the best layer is Y 62 , and…
At the Crafting Table: 1 × Block of Coal gives 9 × Coal. In a Furnace: 1 × Coal Ore gives 1 × Coal. It can be found as loot in Ocean Ruins, Igloo, Village, Stronghold and 6 more. It is dropped by Wither Skeleton. Bought by Villager: Armorer (Novice), common_smith (Novice), Fisherman (Novice), Toolsmith (Novice), Weaponsmith (Novice), Butcher (Apprentice).
It fuels furnaces and furnace minecarts and makes torches, campfires, fire charges and coal blocks. It is an ingredient in 6 recipes, made at the Crafting Table; for example Fire Charge, Soul Torch and Torch.
Yes. In a Furnace it burns for 80 seconds, enough to smelt 8 items.