Assuming you have the X devel package as others have suggested, you may also need to tell the compiler where to find the headers: -I/usr/X11R6/include
#include <X11/Xlib.h> should then work. Xlib is beastly and nasty, so if you aren't very familiar with C (especially if you're easily frsturated) it's probably a bad place to start. Gtk would be better, or even better, simple command-line programs. Gtk is more fun, but a small command line program is probably more sensible. :-) HTH, Havoc
