The surfex package which you can download contains a directory called "doc". This directory contains the surfex documentation in several formats including PDF.
The documentation contains the download and installation instructions as well as a desription on how to use surfex for visualizing algebraic surfaces.
For convenience, you can also download the PDF user documentation from here:
documentation for Linux / Unix / Mac OS X, documentation for Windows.
However, we hope that the user interface of our software surfex is intuitive enough to allow you to work with it without reading the documentation.
Nevertheless, you should take your time for looking at some of the examples in order to learn about surfex's most interesting features. Some are contained in the examples section of this site, some more are contained in the downloadable surfex package.