how to add a custom program in the startup of a computer

Im trying to make a sign for a theater of mine. I made a program called "sign" it displays that text on a monitor located above the computer
and i want to add that program to my startup of the computer.

its a long text art program nothing fancy
just six lines of print

heres how i edited the start

monitor top sign

but thats not lua..

Try

shell.run("monitor", "top", "sign")

I wasn't sure how to use shell
thanks