To generate (render) the above image, do this:
shader plastic.slif you have PRMan, or
aqsl plastic.slif you have aqsis.
prman Teapot_P1.ribor
aqsis Teapot_P1.ribetc.
Now that you can generate an image, try editing the RIB file to change values there (eg. image resolution, camera FOV, light color, etc.). The idea is that the RIB file contains scene data, and the RenderMan-compliant renderer reads that to produce an output image ("a render").
You can now play with dozens of other RIB files and shaders found in other pages in this section of the site. Have fun!