You reach the Void at the end of the first chapter of Darksiders Genesis. To unlock this location, you need to open a mysterious gate. This page of our guide to Darksiders Genesis has a detailed solution on how to reach the Void.
Immediately after entering the Void you have to approach the rock glowing red. This object has an ability that will allow you to proceed.
Approach the object and destroy it. You can do that with any weapon.
After that, you will get Vorpal Blade. It is a massive object that looks and works like a shuriken.
This weapon allows you to attack enemies from a distance and helps you open many secret passages.
Go to the main hall in the Void. There's a blue button on the wall. Hit it with Vorpal Blade to open the passage.
When you go further, you will come across a huge abyss. Hit the blue button at the bottom with a Vorpal Blade to create a gust of air.
Your next task is to aim the Vorpal Blade at the fire and then at the lanterns. This opens the last passage in this part of the map - you have completed chapter 1.
After performing all these actions, you will be able to continue the game.