I’ve got MediaWiki installed, and I know that the files for it are stored on the Micro SD storage in the FreedomBox host computer, but how do I access and edit those files from anywhere, particularly with MediaWiki?
If you want to access your files from outside your local network (i.e. while you are not using your home router), you will need to set up a public IP address for your FreedomBox. Instructions for that are found here: Publicly hosting a site
And if you want to access MediaWiki’s files in particular, you could either (1) use MediaWiki’s interface to access the files and edit them or (2) use SSH to access the files on your FreedomBox (not recommended).
You can learn how to do (1) from MediaWiki’s documentation. They have a very good wiki: https://www.mediawiki.org/wiki/MediaWiki