Your question remains unclear. For instance, given a Virtuoso instance listening for HTTP/WebDAV requests on http://{host}:8890/ that hosts the file xyz.html, you would download the file via a GET request targeting the URL: http://{host}:8890/xyz.html.
Live URL example:
http://id.myopenlink.net/DAV/home/KingsleyUyiIdehen/Public/learn-rdf-turtle.ttl
Clicking on that file will open it in your browser (which also offers a “save as” option).
You can also execute the following form your command line:
curl -O http://id.myopenlink.net/DAV/home/KingsleyUyiIdehen/Public/learn-rdf-turtle.ttl to download it etc…
The Briefcase interface to the WebDAV file system is simply a UI skin which also includes and API for REST-ful interaction etc…