One day when you feel it would be cool to be an author, well why not try and if you don't try you'll never succeed. So, your first step is trying and if you can do that then you're on the right track
Come up with a list of names for your main character.
Now, create the characters appearance, favorite memory, trait, best friend, worst nightmare.
When you have that you can come with a secondary character with the same steps as a main character.
With that come up with a genre for the story whether murder, mystery, funny, philosophical, or whatever you want
Then just come up with an intriguing plot to draw readers in
start on your first chapter and decided if you want it in present or past tense and if it should be in first person or not
Then the book is yours to decide and discover :)
- Or maybe a computer