Unfortunately, the best way to learn the basics is to jump right in.
Unfortunately, the best way to learn the basics is to jump right in. While IGN's Battle Royale Basics and Features guide will certainly help speed up this process by introducing/explaining key concepts, most of this information will be gleaned from in-game experience. Mess around with the pickaxe, try building a wall, shoot a few guns – it shouldn’t take long to understand how the most important aspects of Fortnite works.