Understand the Intro sample.
After you've worked through the Beginner's Guide, the Intro Sample is a great place to go next.
Intro is a simple conversation featuring branching, variables, localisation, a themed Line View and Option View, and voice-over.
To understand the Intro Sample, open it and take a look at the Hierarchy:
You'll find the following:
Dialogue Runner — a GameObject with a Dialogue Runner, an Audio Line Provider, and a script to allow the game to be quit attached to it.
The Dialogue Runner is a Component supplied by the Yarn Spinner for Unity Package.
The Audio Line Provider is a Component supplied by the Yarn Spinner for Unity Package.