The only thing uhttpd is good for, is serving static content. It has no fancy bells, or whistles, like virtual host, or CGI support. All it does is host static files out of a directory for you.
If you are looking for the uhttpd that ships with OpenWRT, you are in the wrong place.
Customize the listening port(Default: 80):
sudo snap set uhttpd listening-port=8080
Customize the serving directory(Default: /var/snap/uhttpd/common) (EXPERIMENTAL, likely won't work):
sudo snap set uhttpd document-root-dir=/media/USB
Toggle output of access logging(Default: false):
sudo snap set uhttpd enable-access-log=true