How to generate procedural terrain in java? (Total noob, HELP!)

So I'm making a 2D top-down game (something like Zelda) and I'm actually new to Java but I'm not new to Game Development and I know how to update, render stuff to the screen as well as how to make collision detection, HUD, GUI. but I want to make the terrain to be randomly generated (i.e like Minecraft). I want a function that returns a value from -1 to 1 or from 0 to 1 that generates random terrain that looks something like this.

I've heard about Perlin Noise, Simplex Noise and all that but the guys talking about the topic seem like pros but I don't understand a word not even from the Wikipedia article. What should I start learning?

I know this might not be a very good question but please just show me a place to start, from the basics of random generation.