Don't do it.

Hosting a public service with no real knowledge of security can only end badly.

Get a vpc, do it there, learn from mistakes.

It's more than just HTTPS, you also need proper authentication, regular updates, emergency updates for critical vulnerabilities, ideally some sort of monitoring to detect potential misuse of the service or any escalations from the service to the OS.

Ask yourself this: If this was your first time driving a car, would you rather do it in an empty parking lot where at worst you will damage the car. Or would you rather do it in a busy street where at worst you can kill someone?