This page will give you some basic resources to understand how to start writing and what it is you even want to write.
DEFINING THINGS YOU NEED TO KNOW:
Fiction vs. Non-fiction - and what each of those very broad categories encompasses
Defining Genres - Do you write fantasy? Or science fiction? Or science fantasy? What is upmarket fiction?
Defining Categories - Adult, NA, YA, MG, PB
Word Counts - Broken down by category and genre (Note: This link will take you off-site. This is such a contentious subject, I decided to leave it to the ultimate experts at Writer's Digest.)
DOING THE ACTUAL WRITING:
Finding Story Ideas - An entire series on where to get your next idea.
Beating Writer's Block
Plotting vs. Pantsing
Best Books on Writing - a post dedicated to outlining which books can help you overcome writer's block and make your writing as strong as possible.
PLOT vs. PANTS
How to be an Effective Pantser
I WROTE A BOOK. NOW WHAT?
What's CP and a Beta and how do I find them?
Go pick a Publishing Path.
Once you've gone through these resources, you're ready to decide on a Publishing Path.