A small installation help comes with the package, but let's do it together :-) -- If Leafnode >=1.4 is shipped with your distribution, it would be the wisest to use the pre-compiled version and leave out the steps 1 to 4.
1.) Be sure that there is no other news server running on your
computer. When you type
$ telnet localhost nntp
you should get an error message. If you get a connection get back to the
prompt of your shell, you should uninstall INN, CNews or whatever you're
running now and comment out the nntp-line in your /etc/inetd.conf.
2.) Make sure that there is a user called "news", check in
/etc/password for the name. If there isn't, create one (either typing
$ adduser news
or using a tool shipped with your distribution).
3.) Unpack the sources:
$ tar xfz leafnode-1.4.tar.gz
and change into the source directory
$ cd leafnode-1.4
4.) Compile the program and install it
$ make; make install
5.) Edit /usr/lib/leafnode/config (it may be on any other place like /etc/leafnode when you use a pre-compiled version of your Linux distribution). The line "server =" should point to the news server of your ISP.
6.) Edit /etc/nntpserver. It should include your local hostname (localhost or whatever your computer name is, the command hostname should help you). If in some startup file like /etc/profile or  /.bash_profile the environment variable is defined, you should adjust to your computerīs name as well.
7.) Edit the /etc/inetd.conf: Make sure that there is no line beginning
with "nntp". If there is such a line, comment it out putting a "#"
before it. Then add the following line:
nntp stream tcp nowait news /usr/sbin/tcpd /usr/local/sbin/leafnode
When someone (for example you :-) connects to your computer on the
NNTP port, leafnode is started as server process.
8.) Go online and run the program "fetch" as root or news. The first time fetch is started, it will download a list of your ISP's newsgroups. This may take some time depending on the speed on your connection and the number of groups your ISP has in its active-File.
9.) Start your favorite newsreader (slrn, (r)tin and knews are not a bad start) and subscribe to all your groups you read. Be careful not just to subscribe these groups, but also to enter them, even when they're empty.
10.) Start fetch again to download all the news of the groups want to get.