Answer: Starting out as a writer who has never submitted anything can make such subjects seem daunting. But every great writer has gotten their start somewhere. Every great writer took that first step. You should, too.
First, you need to research the markets (listings where you can submit your story). To do that, you should consult a current year's version of The Writer's Digest Novel and Short Story Writer's Market or if you don't have one available, you can search online at Duotrope's Digest by picking the options in the drop down menus that defines the parameters of your story by genre, word count, etc.
Once you've identified markets to send your story to, you MUST go through their submissions guidelines first. Writer's not following submission guidelines is the #1 problem that agents and editors report. It will almost definitely ensure that your story will be rejected. Make sure you know if the listing allows for simultaneous submissions or not. Make sure you know what format they want the story in, what information they want on the front page, etc. (Be sure to click the links within this paragraph for extra reading on the subjects.)
Once you have edited and revised your story to the point where you are happy with it, you've researched the appropriate markets, and prepared your story to their specifications, then bite the bullet and send it. Even if you get a rejection, look at it as a learning opportunity. You never know unless you try. Even if you get a rejection, it doesn't mean the story was bad.
Most importantly, after you submit the first time, it gets easier and easier to do. One thing to remember is never to stop. While you're waiting on responses from publishers, write more and submit more so you won't be stressing on that one submission.