Are there access to my files from the internet?

Hello! I am a new here. I have a question. Case:

1. I created Joomla Ubuntu droplet
2. I connected to droplet using putty.exe
3. I launched MC file manager in order to look at list of folders and files
4. in the parent directory I found a number of folders: bin boot dev … … … var
5. as I understand files and folders for website are located at var/www/html and access to these files could be organised somehow from the internet…
6. The question is: are there any ways to get access to the rest list of files and folders (which are NOT located in var/www/html). I mean, should I protect these files somehow in order to prevent unathorised access to these files?