This tutorial shows you how to install Photoshop patterns by downloading patterns, placing files and loading patterns. Here are more free basic tutorials.
1. Download Patterns
Find the patterns that you want on the web and download it. The Adobe Photoshop patterns file will be in a PAT format.
2. Place File
On desktop, Finder > Applications > Adobe Photoshop CC 2015.5 > Presets > Patterns > drag PAT file into the folder.
3. Load Patterns
In Photoshop Layers panel, double-click a layer.
Select Pattern Overlay > open Pattern Picker > click gear icon.
Select your patterns > click OK. Done!