For information on installation, read INSTALL.
For information on the Unix implementation, read Readme.unx.
For information on the VMS implementation, read Readme.vms.

If you are not running Unix or VMS, read both.  With some luck the
information you seek will be there.  You may want to write a file with
the operating system dependent routines.  For examples, look at os.c
(which includes one of the following), unix.c, vms.c, and unknown.c
(the default for an unknown operating system).