I've been writing a fantasy saga for several years and I've built up quite a collection of lore, and worldbuilding. While I can give a short, dirty description of the main Arc. I find it hard to discuss my story in detail without coming off like a rambling, over exited fan boy of my own story.

My question is this:

How can I effectively delve into the complexities of my superfantasy narrative without overwhelming my audience with excessive details, while still maintaining a coherent and engaging discussion, and getting across my primary themes?

The obvious answer I guess is to just write the story, and while I have more than enough I formation to do so, along with a solid outline, I really struggle with prose and the more miniscule details, but in order to ask for help on some of these topics I need to be able to effectively communicate my overall story.