Have script, need director!

There must be dozens of books on how to write a screenplay at Amazon. Read a whole bunch of them.

Then go to imdb.com and look up every movie or series that you could call grand space opera. Click on their creators and check their experience before they sold it. Notice how few of them exist. Also check names of major authors of space operas and see if any of them have ever sold a script or even the rights of their books. Realize that everybody in Hollywood hates grand space opera.

If you have the time, of course.

Direct it yourself. From Argo: