You know you want to be an author...but you don't know what to write about. Coming up with a good idea is one of the hardest parts about being a writer. Don't rack your brain and beat your head against the keyboard. Go hunting, and start finding inspiration.
Knowing who you are and what you like is the best way to find writing inspiration. Are you drawn toward romantic movies more than others? Do you choose funny comedies more when you watch TV, or dramatic reality shows? Pay attention to your own interests, and you'll know what sort of stories you ought to be writing.
For example, me. Given the opportunity, I'll watch "Dragnet" and shows about real crimes all day. I'm particularly interested in unsolved cases, and specifically interested in the ones involving missing persons. This is why you can often find this element in my books. My stories frequently revolve around what's unknown.
I find inspiration all the time simply by following my natural preferences. It usually happens when I ask questions. What would this situation feel like? How would I react to a crime like that? What if it was the mother who did it all along?
When I can't stop asking questions, I know I'm inspired. Finding inspiration may be as simple as watching one of your favorite movies. So try getting inspired, and see what happens.