How it works...

You have created a new Unity project with the Fungus asset package.

You have added a Fungus Flowchart to your scene, and also added two characters (each with a text color and a portrait image).
For the Block in the Flowchart, you added to Say commands, stating which character was saying each sentence, and which portrait to use (if you had added more portrait images, you could select different images to indicate the emotion of the character speaking).