You can find an overview of all Varify.io® functions in the user documentation.
Under First steps describes how Varify.io basically works.
Under Tracking & Setup you can find out everything about how to connect Varify.io® to your analytics tool and how to evaluate your tests.
Under the item Targeting you can find out how only the visitors who are supposed to see the test can see it.
The area Advanced is aimed at experienced users.
Under Function overview you will find all the editor functions and learn how to use them.
You will also find under the section Tutorials useful Step by step tutorials that show you how to use Varify.io.