A private network is very simple to establish, but first you should think, if it is really necessary.
You can serve those files via Gnutella and verify them by putting magnet-links on your page, which the people can cick to get the download.
With Phex you can now also distribute collections of files to your users automatically by giving them
a magma-list.
If you want to use the search funktions of p2p-Programs, so your material is easier to find, you can also use Phex and make it use a
Private Gnutella Network as standard.
Best Wishes,
Arne