Websites such as Archive of Our Own (AO3) are good options. They offer a free space for sharing your stories and have a wide user base. But make sure to follow their guidelines.
Well, there are several options. Amazon Kindle Direct Publishing is a great choice if you aim for commercial success. Another option is Royal Road, which is known for fantasy and sci-fi novels. Also, consider posting on your own website or blog to have full control over the presentation.
Well, you might look into platforms such as Archive of Our Own (AO3), which is great for various types of stories. Or, if you prefer a more professional setup, try pitching to literary magazines' online editions. Some well-known ones include The New Yorker and The Atlantic. Just make sure to read their submission guidelines first!