Some people want to write a story, but don't think they have the talent. Others don't start writing because they either think they don't have a good idea or aren't sure what type of story they should write. Everyone has to start somewhere and practice is a big part of developing your skills. However, before your start practicing, do some reading and watch some movies. Consider it homework. Both of these can help you learn what topics interest you and demonstrate the basics of telling a story.
     The very basis for my first novel was a short story I wrote to answer some unanswered questions when I wondered what happened in the untold portion of a story of my one of my favorite crime dramas. Have you ever been left hanging, the writers never explained certain situations, or there's not enough back story about your favorite characters? You already know a lot about how the characters respond to certain situations. Write your own episode for your favorite television program. The problem with this method is that you're relying on the work already done by someone else. It's great as a means of practice, but you must then develop your own voice so your story becomes an original work.
     Once you understand the basics, it's time to start writing. Don't start with a novel if you're easily discouraged and will give up if you first attempt ends in failure. Start small. If you keep a journal, expand one of those entries into a one or two page story. Write about an event from your past that had a big impact on your life. Develop your imagination by viewing the world through the eyes of a pet. Any of these can later be used as the basis for your novel. By writing a variety of short stories, you can find the style that fits you best and the topics that interest you the most.
     But what if nothing you've written in practice sounds like a great idea or you're not interested enough in the topic to write 80,000+ words? Watch the world around you. Ask yourself what you're most passionate about. Anything that stirs an emotional response within you is something about which you'll have a lot to say. Again, start small. Write a fictional account about missing children, a sporting event, or how you view the future. The more you know about the topic, the better. Use your personal experiences to further develop the plots.
     Even if all of the practice still doesn't lead you to anything you feel will make a great novel, you've improved your writing skills. Take some of those two or three page short stories and make them longer. You now have a collection of three, four, or more 10,000 word stories. You can submit those for publication. It may also surprise you to discover that, by combining two or more of your short stories, you can produce a novel.