This document provides a tutorial on how to create a custom brush in Adobe Photoshop. It outlines the steps to select an image area, desaturate and adjust the brightness/contrast to create a grayscale selection, save it as a channel, fill it with black to create the brush shape, and define it as a new brush preset that can be used in other projects. Creating custom brushes allows for more unique backgrounds and images compared to only using the default brushes.