You'll need to create your own Roku channel. There are lots of ways to do that including using the Roku SDK and Direct Publisher. The method you choose depends on whether you have time and/or experience for creating a channel, and, how much you want to spend. Yes, there typically is a cost since you'll need to store your video content on a server. Having said that, Roku's Direct Publisher platform is one of the easier methods for getting up and running with a new channel.
FREE Windows desktop software for creating and managing Direct Publisher MRSS, JSON, and FireTV feeds @ https://github.com/rrirower. No Programming knowledge required.
@Baradanikto is correct , you might consider creating a Channel for your content , then share your channel with others + it will be available in the Roku Channel Store so anyone searching for new content will be able to find it.
Building a TV Channel can be easy … if you have a right tools ===>> https://tv-channel.info/