Many of the world’s greatest writers like H.G. Wells, Charles Dickens, and even J.K. Rowling don’t have any formal college education in writing.
The trick is to write a great story and learn how to market it. If you decide to self publish, most of the marketing will be in your hands, so be sure to do your research. A traditional publisher will handle much of your marketing, but you should still be prepared to do your part.
If you want your book to do well, you need to write it well. Keep practicing and improving your skills. You can’t be successful if you don’t try.