Using Cloudron has been really easy for a person like me (with little prior server mgmt skills). When I first started out, the only video I found to help me visualize this process was this one https://m.youtube.com/watch?v=kjCqd6Bwc78 (installing cloudron on Vultr server guide).
For Ghost specifically, while Cloudron updates the Ghost package version, it does not update your theme. I use WinSCP to connect to the server, see the files/folders visually & make changes (to the theme, delete stuff) if needed. After that, remember to Restart your app on Cloudron dashboard for changes to take effect.
In addition to Cloudinary (a great choice) that scooke mentioned, I’m using https://postimages.org. A little roadblock we’re having now is the ghost Subscribe function + Cloudron email SMTP. It’s not taking in the new subscriber’s email properly.
For security, disable password login & use SSH keys to access your server. Change from port 22 to 202 as recommended in the docs. https://cloudron.io/documentation/security/#securing-ssh-access
I can share with u now that I have learned a lot on this exploration. The folks on this forum have been so helpful & generous in sharing their knowledge and tips.