Congratulations on taking the first serious steps toward becoming an author. Did someone tell you it's easy? They lied. Did they say it was fun? Well, sometimes. Did they tell you that it takes a lot of work? They should have warned you! A big part of writing is discovering what works best for you. Are you an 'outliner' or 'pantser' like me? Pantsers (aka explorers or gardeners) do not outline. We fly by the seat of our pants. We explore our story along with our characters. Sometime we go down the wrong path and have to backtrack and rewrite, so our work is on the backend of the story, where an outliner invests their work in the frontend. But the first thing we all have to do is get the story down. It will not be perfect. Your end product may be so different you won't recognize it compared to the original. You may have to tuck the story away in the dresser drawer. Many successful writers have 'drawer novels.' Several novels, even! The key is to analyze other authors (including TV/movie script), learn from them, and keep writing. Nobody ever started out as a skilled craftsman. They practiced and learned.
It's a tough endeavor to become an author. You may want to pull your hair out in frustration. You may want to knock your laptop off the desk. But nothing will come close to the feeling you get when someone tells you how much they liked your work.