How would i make this script in C language? Really easy to do, im just stupid?

I want to make a program that when intalled says "onshut down - message pop up "Goodbye". or something in the c language, how would i do this?


Also if an image could pop up instead that would be good if poss.

How would i make this script in C language? Really easy to do, im just stupid?
Uh, for which operating system? I could give you the code for Windows, but you would need a Windows compiler, linker, the Windows header files, and the import libraries installed on your computer.


(If you're using a DOS C compiler, then you might as well forget it.)