How do you go about when you want to start writing a short story?

I thing this is really difficult, but I still want to try it out, to see if I am capable of writing a short story, and eventually maybe a novel.

Previously I have written poems and ideas that have not proven themselves long enough or good enough to make out even a short story. But I think this is because I have doubted myself in the past, and because I have always been under the impression that I do not have what it takes. Luckily I think otherwise now. Or, at least: now I know that I can not know if I am good at anything until I have tried. Besides: everybody needs practise! :)

First and foremost I will sketch down my ideas. Secondly I will have to look up words to see if I have written them correctly. I know I probably have a lot of writing errors at the moment, but I will get better i time, I promise - right now I'm kinda like Bambi On Ice. Hopefully I will turn into Sonia Henie on Ice eventually.

Take care.