1) Connect with your target audience individually.
2) Get to know them and their pain points better.
3) Choose a platform to host your community that can suffice your needs like running a forum, hosting events, sharing messages, etc.
4) Share regular updates about your product, get their feedback, and keep them in the loop.
Hope this helps! :)
The first (and hardest) step is building a community to engage with! Reach out to people, interact in spaces where they frequent, chat with them, get to know them, understand their pain points, and show them that you've got their best interests at heart. You'll build a community in no time if you're motivated, consistent and genuine.
Best of luck!
Wylo