Ok. You will spawn in a world. If there are trees nearby, you are good for now. If there aren't any trees within 50 blocks from spawn, I advise you to delete the world and start a new one. (especially if you spawn in an ocean biome.) You will need to build shelter. To make a regular sized house, you will need at least 2-3 stacks of wooden planks. Then you make your house. (quality is not that important in single play.) Then you will need a sword and a pickaxe. With the leftover wooden planks, you should make a crafting table (or workbench). Craft a wooden pickaxe for now. By the time you finish all of this, it should be night. Do NOT go outside. (if you want to survive that is.) Just mine for now. You may find a lot of iron or coal in the mine. DO NOT mine iron with an wooden pickaxe. Heres a chart: wooden pickaxe: Stone, coal. Stone pickaxe: Stone, Coal, Iron, Lapiz Lazuli. Iron pickaxe: Stone, Coal, Iron, Lapiz Lazuli ,Gold, Redstone, Diamond. Golden Pickaxe: Stone, Coal? Diamond Pickaxe: Stone, Coal, Iron, Lapiz Lazuli, Gold, Redstone, Diamond, Obsidian. Got it? I guess you just live like that... Just keep this up and make armor and better stuff to survive. Hope this helped!