This tutorial will teach you how to make a scene in which a marker will speak as another NPC, when NOT in direct dialogue with the player (see Talking Activators for things like the DB door). An example of this is when you pick up Meridia's Beacon in game, and Meridia speaks to you. The actual actor of Meridia is nowhere near you - in fact, she's disabled. An xMarker is actually speaking with her voice. This will allow you to have the NPC speak ANYWHERE you want, without having to move the NPC around in case they need to be elsewhere.
You should understand basic quest/scene design.
You should understand basic quest/scene design.