lol sure :) I'm not the best out there but I guess I know basics.
First you gotta have a story in your mind, even if it's not an actual story just a random though but you think would be a good story then keep that in your mind. From that think of what kind of story you would see it in, like White As Snow, I figured it would be a teenager, then I thought I'd put some extra in it, like the highschool, the friends, things like that.
Some people like making it up as they go along but even then they still have an actual plot in their heads like who the characters are and they use that to create a story so anything can happen depending on those characters.
If possible you'd definitely need a summary of the story, mostly so you don't lose track of what the plot is supposed to be. You might want to write down the characters and their details for yourself somewhere so you don't forget anything (I forgot what my characters looked like but with help remembered them and this time wrote it down so it wont happen again).
This is basically how I write. That's how I structure it if I bother to structure at all (the other stories I have up here winged the whole thing no structure whatsover so I have to re-read the whole thing to remember what I was writing about but that's fine I'll start working only on one book so I don't lose track).