Making a first book, but too many ideas and don't know how to start
Hello everyone
Brainstorming hard rn
I am autistic and have a new hobby, per se, and I want to write a book, as I have been inspired by George R.R Martin, Tolkien, J.K. Rowling, and George Lucas. as well as anime and manga. So it's a Fantasy setting ofc.(Hence why I'm in this subreddit lol)
How would one start, as I have a lot of lore in my head but don't want too much where it becomes overwhelming so I can't make characters? ad need help generally writing.
Set on a continent surrounded by a giant ice wall with other continents beyond it. ( I got inspired by the weird Flat Earth theories)
Basically got wyverns, wyvern hybrids, man and other fantasy aspects.
pls help