From the DV Dictionary tutorial, I see:

Dream Guide
1. A dream character who helps you knows more that the average dream character about your dream; some believe that it is a manifestation of your subconscious.

And I've see many references to this idea in threads and people's DJs. But I'm unsure able how to find/create my own DG. Is it one person from my real life that I will symbolize in dream? Is it an imaginary character? How should I approach the idea? What are some experiences that people have had?