I'm not sure where you ran into trouble, but if you are asking what URL to give her to access your server you can follow what I wrote below.
If you have registered a dynamic DNS name for your server (you mentioned dns in your post), configure HFS to manage it with the Dynamic DNS updater wizards. At that point its just a matter of giving her the dns name. For instance, if your DynDNS is fysack.dyndns.org and your server is listening on (or rather your router is forwarding) port 8080, then the URL to your server would be
http://fysack.dyndns.org:8080/ The port number can only be ommitted if port 80 is used; however, many ISP's block port 80.
Obviously, make sure your default.html is in the virtual file system.