Thinking, but where to start?

Hello people of fimfiction! (Well how else would you read this?)
I have an idea. Bout a STORY! WHOA!
But I request some help.
I have been thinking about an HiE story (Like the most original story yet).
I'm thinking about a Russian OC as it is seldom to see any stories with a Russian in them (Apologies if I am mistaken), and also some twist if that would make things more interesting.
I might need a lot of criticism (try not be rude or something) as this is my first story.
I don't think not having English as my native language is a bad thing as I speak English 50% of the time.(I'm South African and speak Afrikaans at home but really, I can switch between the two languages in mid-sentence, so that is no problem.
So any help will be accepted and highly appreciated.
(Ugh like every sentence is a paragraph!)