It is remarkably difficult to write a story with no comments or critics to help you along the way. That is why I publish my stories on Wattpad, a writing platform that anyone can post anything on. The problem with Wattpad is it can be a little explicit. You need to be careful with what you search. If you are mature enough to get past it, I would suggest posting it on Wattpad.
There are other ways you can post your stories, though. You can upload it to the internet in the form of a PDF, but it makes it difficult for readers to comment. There is always email, but not nearly enough people check their emails anymore.
There are many other publishing platforms, so to cut time, I will post a link at the bottom of the page, along with one for Wattpad and google drive.
Writing online is not a requirement. I know many people who prefer writing with paper and a pencil. If that is the method you choose to use, make sure to keep everything organized in a binder or a notebook. The downside to writing with a pencil and paper is publishing. If you write your story on a computer, the publishing process goes smoother.