how to make a daemon

[Steve Cohen <stevecoh mcs com>]

I have written a little program that listens to /dev/ttyS0 and every
time it sees
a byte, it sends that byte out /dev/ttyS1 and also through a
TCP/IP socket.
This program runs on a linux box that is basically used for nothing
else.

I would like to have this functionality constantly running on the box.
To do
so, do I need to make my program a daemon, and if so how?  Basically
this program needs to run with root privileges.  I have to log in as su
to get it to work.  I want it instead to happen automatically, so that
if the machine goes down, it can be rebooted and do what it's supposed
to with no further interaction.

Any suggestions?