How to selfhost applications

I am trying to run a container with baserow and i am running in to a problem.

i have Nginx proxy manager as a reverse proxy. i am able to reach baserow using my proxy host setup but i can not figure out how to publish applications. i cant open a demo view of my application because it is not published. on the web version free tier i can host via baserow subdomain but how do i do it when i selfhost?