Interaction with other writers and their stories is the best way to build an audience. Join writing groups, book review exchanges, establish friendships with Wattpad writers on other social media, etc. These connections will naturally result in spreading your story out there. But it takes time/dedication, and you have to be willing to help out other writers if you want them to help you. Add stories to your reading lists, read stories that are similar to yours and comment/vote on them, follow people, and have a genuine interest in their work (people can smell fake interest from a mile away). Aside from all that, publishing new chapters on a regular schedule is super important. Weekly is best, but as long as you’re consistent, over time you will see the benefits take effect. And whatever you do, DO NOT advertise yourself/your story on another author’s profile or in the comment section of their book. That is the number one rule of etiquette on Wattpad. It comes off as wanting to leech off another writer’s success and can quickly earn you disfavor in their eyes and the eyes of their fans/readers. So not only is it rude, it’s ultimately counterproductive to your goal.