Help me, grapich function in Lisp

Hi,
I'm a student and I have written a program in Lisp (my first complex program) using this IDE Allegro Common Lisp.
Now I want to build something graphic, for example a simple window and draw some polygon and others graphics object, but I have looked for some graphic functions.
where can I find graphic function with example (in site web) or better some tutorials ?
I don't know if I have to install particular libreries in my IDE, Can you help me?

Thanks a lot...Bosola C.

I don't know much about the details, but you can look for stuff here:
Graphics toolkits
Graphics libraries

The Allegro IDE ships with its own windowing system called Common Graphics, which looks like it would need no additional installation.