How to write a clear tech. exercise?

Question

Documentation

Hello everyone. I know that people here are knowledgeable in various fields and would like to take the opportunity to ask for advice. There is an idea to write a service, start as usual from the web, but when I try to write a technical specification, I start to swim in what I really need and in what I would like, besides, I don’t know how to implement this or that functionality, and frankly, I get confused in my thoughts. It is not possible to order technical specifications, due to the complete lack of budget, I tried to find out how much it would cost to develop a web application for which there are no templates and ready-made solutions, the price tag turned out to be awful, I try to comprehend the necessary wisdom little by little, but due to the lack of those very .tasks again begin to swim in thoughts and ideas. How to streamline thoughts and put them on paper in an idea that is understandable not only to me, and how much detail should I paint everything?

Answer 1

like this
www.artlebedev.ru/kovodstvo/sections/167
the biggest detail is Mindmaps, for example

Answer 2

I think I know you, you are not talking about your savings service now?
I'm sorry for the offtopic

Answer 3

I advise you to start with Mindmaps and web service prototypes. And already on the basis of them to write a technical task.