How to create a process?

Hello thanks for all the help so far. I have the G++ compiler working
in the angstrom 2.6.28 image using command line stuff, and have
successfully made a hello world routine. I was wondering if anyone
knows how to make a c program that runs like a process, or something
similar. What I mean is I would like to create a few c programs that
will run on boot up, but will not disable me from logging into the
computer. To start I would first just like to run a simple led
blinking program at boot up, but still be able to log into and get
around in the shell. Anybody have any thought. I am used to
programming a microcontroller, where there is one main program
running. I would like to use the ability of the SBC to run multiple
programs at the same time (not exactly at the same time it just looks
like it because of time sharing...) anyways let me know if anyone
would like to let me know how to do something like that.
Thanks a lot!!

Linux has a standard set of files (almost always shell scripts) that
are executed by the kernel as the system is brought up and shut down.
The simplest thing to do is add a new shell script containing the
commands that you want to run on startup. That way, it is part of the
standard process and everything continues to work as it does now, but
with your app(s) running also.

The files are stored in /etc/rc?.d (where ? can be 0, 1, 2, ...). Each
one is for a particular stage of startup or shutdown. You most likely
want to add yours to the /etc/rcS.d directory. Take a look at this
page for some quick general info on the startup script process:

There is lots of other information out there on this process and the
rest of the boot process, so if you dig around you can find more
detail and examples.

If you are in the process of learning embedded Linux stuff, I highly
recommend the book "Embedded Linux Primer", by Christopher Hallinan.
It covers a terrific range of information on how Linux works in
general and embedded Linux in particular, and is written in such a way
that you can skip around to the parts of specific interest.