@elena I see you already have a well-configured and attractive Ghost site. The Docker version of Ghost is easy to install. Follow the instructions here to the letter: https://docs.ghost.org/install/docker . It's important that the server on which you install Docker and Ghost is clean and has no other packages installed, such as MySQL or a web server. A (sub)domain must then point to the server. The installer expects a freshly host, and anything you do differently may cause conflicts or configuration errors.
️ my adventures in #selfhosting: day 259 (slow down edition) 
