First, you'll need to download the game from the Epic Games website - it's free, so no excuses! Once you've got it installed, you can dive into the game's two main modes: Battle Royale and Creative. Battle Royale is where it's at, though - you'll drop onto an island with up to 99 other players, and it's every person for themselves.
The gameplay loop is simple: scavenge for gear, build stuff, and take down your enemies. But trust me, it's way more fun than it sounds - the thrill of sneaking up on an opponent, or making a daring escape, is hard to beat. You'll need to stay on your toes, though, as the island's "storm" will slowly close in, forcing you to fight it out with the remaining players.