How to read documentation?

Hello! I just start to learn phaser and I start with its tutorial Making your first Phaser 3 game. There is, for example, a code like this:
var game = new Phaser.Game(config); this.load.image(); this.add.image();
And I want to read about methods load or add of Phaser.Game object, but I can’t find it in documentation. I open this link Phaser 3 API Documentation - Class: Game, but these methods are not there

:wave:

Start in https://newdocs.phaser.io/docs/3.55.2/scenes.