The first step is originality.
The next step is emulation, aka copy others.
In all seriousness just do what I'm doing. Write a novel based on the stories you like, and add your own little twist. Then do that again. Then write a completely original story that you don't upload yet when some random four-parter you foolishly chose to do, and don't know how to finish starts pissing you off enough to make you regret the whole thing.
Simple.
If you're agonizing over not being good at storytelling, then you have an idea of what you want to do. Post some bullet points about what's unique about what you're trying to write, and then get some of the more experienced forum users to give feedback, one of the threads right now has a guy who wants to give people harsh feedback, get him to look at what you have.