Part of it's going to be seeing if you want to approach it the same ways you approach poetry - like, where do you start? Is it a line, a concept, a tone?
'Cause there are some prevailing schools of thought about starting with character or with plot but they're mostly kind of reductive. Like, you need both of those, but not necessarily to start there. The core component of a narrative is to have at least one character who wants something. There's a whole lot of places to go from there, and a bunch of ways to arrive there (like, if you start with the concept of transcendental dolphins you might still end up with Arthur Dent; same with starting with the line "I never could get the hang of Thursdays" ), but that's the core bit.
Since you know how to stick words together, it's mostly going to be form, I guess, so I'd suggest trying a known structure as a first foray, just to see how things have to be blocked out. A three-act structure or kishotenketsu or retelling something famous (fairy tale retellings are some of my favorites) could be a good way to see how the rhythm of it works. There's reading you can do, about structure and the hero's journey and w/e, but that makes it really easy to overthink, and just writing out a structure you know (like action movies or murder mysteries: you know how they go, since they all go the same) can make a lot of it make more sense anyway.
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