Michael said:
I'm making a program in C, in which I would like to be able to show
images and to draw on the screen. How can I do that?
This depends to a large extent on which platform(s) you wish to target.
Basically, you need to find a graphics library that is supported on
(or at least available for!) your platform, and use its routines to do
graphical things you want to do. The following list is most definitely
non-exhaustive.
MS-DOS: (Borland) BGI, various Microsoft C extensions, Allegro.
Win32: Win32 API, GTK+, SDL, Allegro.
Linux: (at least) XLib, GTK+, SDL, Allegro(?).
Atari: last I checked, Atari machines had a graphics library in
ROM, called VDI.
Mac etc: no idea, sorry.
Discussion of how to use these libraries is beyond the scope generally
accepted as topical by comp.lang.c regular contributors, so you will
need to find a newsgroup that deals with the platform you are targeting
if you want further help.