1. There is no unspecific tutorial on sharing files.

2. You have found this newsgroup, thats GOOD! Here you will find most of the information needed.

3. It is quite normal that you ´can´t download any files. If you get search results your gnutella client is working perfectly well.

4. Use Furi, I just love this client (and I am in this filesharing thing for quite some time now).

I hope this helps you at least somewhat.