So if you've watched me demo the technique you've seen me go through this reenactment, but I'll try to include different details and be a bit more concise so you can use this as a reference as you create your own project. 

My starting point was an article I read on vice.com on illegal kerosene refining in Syria a while back. There was something haunting, cinematic, about the cover image - for a couple of months I kept returning to the image, thinking about this boy, this process. I began to ask what ifs and imagine a story involving the boy. Could I dramatize the facts into a short screenplay, bend the truth into invented drama? But for the most part I procrastinated, I just basically just stared at this image above my desk for a couple of months:

I figured maybe one way to start generating ideas was to go back to the original article and highlight words, phrases, details that I thought I could fold into my story, or at least be triggers for my own ideas. So I took each of those highlighted bits and converted them into a post it note like so:

Cool, things are starting to look a bit chaotic as if a mad genius is at work - but I still haven't 'invented' anything of my own. Let me at least try to organize my thoughts, group my post-its thematically:

In the upper right corner you can see I've grouped any post it notes from the article that I think could be used to describe the boy in the image, in the upper left corner I've got some post-it notes related to the process of kerosene refining (clearly I'm interested in those details) and the rest on the bottom left are jut random details. Again, I'm organizing it in a way that makes sense for me, organically, I can always change my mind later on, or try variations and photograph them for comparison. 

Okay, so again I got stuck, I still haven't really taken 'ownership' of the material yet and started inventing things of my own to put into a potential story. But I have a strong sense this boy will be the main character of a future piece. 

More weeks (months maybe) pass by and the image of this little boy continues to sear into my brain - maybe I'm procrastinating, waiting for inspiration to hit. But finally it does, I find another image from a different but related source that I think could be the owner of this makeshift refinery and could make sense in this fictionalized world I'm slowly creating: 

So I tack that image up on my wall:

Cool, I'm starting to get somewhere. I'm starting to put together preexisting elements in new ways - I'm starting to invent. But I'm going to need a lot more material. Luckily that new image triggers some ideas of my own, I begin describing this new character, coming up with post-it notes for each detail, things he maybe say, the way he acts, etc. Again, I have no idea if any of this will make its way into my final story, I'm just trying to create this world and think about the connections between the different elements and characters:

After another brainstorming session I discover that I think this little boy should have a father figure, a grandfather that has travelled with him to this place. And the image of the owner-cowboy has inspired an entire scene. I jot those ideas down on post-its and regroup them so that I don't get lost in the mess: 

You may not have noticed, but each of these photographs are progressively wider, as I get more material on the wall - in your case you'll start off with a very tiny idea and if you're patient it will gradually build up. Here in this reenactment I've made it seem easy, but to be honest this process took me a while as I allowed things to kind of simmer together and to find a fictional story out of the real elements. 

I now have three characters, I've got some sense of the story world's settings, I know I want to use the very tactile process of kerosene refining in my script. I think the little boy will be experiencing nightmares during the short story that are partially inspired by what he witnessed earlier on and by this hellish process. But I'm starting to get a bit lost in what I have (and don't have yet) and if I even have a 'story', a narrative, or if I just have islands of details. So let me try to organize these scraps into some kind of logical order. Let me see if I have some kinetic energy, if these elements are bumping and moving into one another. In my case, the choose to structure what I have in a 'beginning-middle-end':

 

This is still very skeletal, lots of gaps, lots of unknowns, but I feel comfortable going to my computer to begin fleshing out my first draft, using this as a kind of outline and guide. Again, I've made this look linear and easy for the sake of the reenactment - in reality coming up with the first draft of anything, by any technique, is difficult. 

Here's the first draft of my short script, I'm not entirely happy with it, but it's at least a rough beginning. Now it's out of my head and on the page and I can see what scenes, arcs, dialogue, etc needs improvement. That's the whole point of this exercise, to make the images and ideas in your mind into something physical so that you can refine it over and over again until it's sharp and stands on its own two legs. 

As a reminder, in your case you can start off with anything: something real, something invented. Feel free to take your developing it. And when you get to a stage your comfortable sharing give us a snapshot of what you're working on. 

Leave me a message if anything wasn't clear!