How do you trigger dialogue?,How can I activate dialogue?

I am using the Parley Dialogue system and I am going to make a socializing game. I would like to know what code I must put in to trigger a dialogue scene to start when you bump into an NPC. I’m sorry for asking this, I am very new to programming.,I am making a game using parley dialogue. I want to make a chat scene activate when I bump into somebody. What code do I put in to make this happen?

this tutorial shows how to use triggers, which is what you can use to detect closing in NPCs:
3D Physics - Unity Learn