All my life, I wanted to be a writer. I'm not sure why the child me decided that was what I was going to do when I grew up, but it did. Almost from the moment I knew what books were, I wanted to write them.
The magic of words! Putting them together to create stories that other people would find interesting. It would be awesome!
But the reality of the profession is not all glamour and accolades. It's not easy, and writing the book is the least of it. After the book is done, there is finding a publisher. After you find a publisher, or decide to publish it yourself, there is marketing/promotion. There is always something else to do. But don't let that fact scare you away.
If you really want to be a writer, you will do it, no matter what the deterrents--but you need to go into the profession with open eyes.
Where do you start?
Sitting at your notebook, or computer, or typewriter and beginning to put letters together into words. Yes, it is that simple.
But that doesn't mean that the words you come up with will be a masterpiece out of the gate. When you finish your first draft, the party has only just begun. Then you need some real, critical beta readers to give it a look. You need an editor who will tell you what works and what doesn't.
Then, once your work is as polished as it can be (in your opinion), there are query letters or submission guidelines to check out. Submission packets go out. The WAITING begins.
When you are finally accepted, then there is the editorial period with the publisher. After the story is finally COMPLETE, and published, then you will be pushing that book from now on.
But don't despair. There are places to go for help.
Writing: Writer's Village University -- online classes
Writer's Cafe -- challenges and feedback
NaNoWriMo -- 50k words in 30 days -- good way to push yourself forward
Submitting: Writer's Market -- online version of the best list of mainstream markets
Ralan.com -- best list of speculative markets
several Open Call groups on Facebook (just ask to join.)
Promotion: Great challenge for building platform going on this month at Writer's Digest (still time to catch up)
CafePress -- marketing promotions
VistaPrint -- business cards and promotional items
4Imprint -- marketing promotions
Of course, that is only the tip of the iceberg. There are thousands of websites that can help a beginning author get started. Just go into the profession with your eyes wide open. :)