Welcome to the Roku Community, @David_Moore!
Thanks for reaching out. We'd be happy to share further information about this.
Yes. You should plug your Dish TV into the HDMI port of your Roku TV and you should use the HDMI (eARC) port to plug in your Roku soundbar.
To help you learn more, you may check this support article related to this: How to connect a surround sound system to your Roku TV™
Feel free to reach out if there's anything else we can assist you with. Hope this helps!
Best regards,
Carly
Carly Y.
Roku Community Moderator