Writing for pleasure or business certainly isn't easy and it's an emotional roller coaster where you can feel like the king of of the world one day and complete loser the next. This is something you need to know before you get too deep into the game.
It all starts before you even write your first word. You battle with your own inner demons that are telling you that you can be the next Stephen King one minute and total hack the next. Most people can't get past this first barrier.
If you actually make it to putting pen to paper, then you'll start to question your writing. I know when I write, I think it's all complete and total crap as I type and it isn't until I go back and read it that I start to feel like “hey, that's not too bad.” I go through this page after page.
When the story is finally done and completely edited to the best of my ability, it's time to send it on for publication. Odds are by the time you're finished, you think your story is awesome. If you didn't, then you wouldn't try and get it published.
You may send it out to one place at a time or to several places via e-mail and/or mail. You hope that it's going to be snatched up right away, but be prepared for rejection. It may not fit the publisher's criteria, it may not have been their cup of tea or they didn't even get a chance to read it, but it was rejected and rejected and rejected.
Rejection is part of the game as well. No one gets accepted every time, especially when you're starting out. Be prepared to run the gambit of emotions especially when it finally gets accepted.