The files in the subdirectory examples in the source code show the complete public API in action. Briefly, if you know how to use the stdio.h ANSI C calls, cole API will be very easy for you. If you use autoconf in your own proyect, the included file cole.m4 may be useful for you. It contains the m4 macro AM_PATH_COLE that detect the presense or ausence of the cole library in the system being configured. To use it: If cole is not installed in your system (i.e. aclocal can't find cole.m4), add the content of cole.m4 to your own acinclude.m4 file (create it in case you haven't one). Add a line like AM_PATH_COLE(2.0.0, [LIBS="$LIBS $COLE_LIBS" CFLAGS="$CFLAGS $COLE_CFLAGS"]) to your configure.in file. Here we are requesting for cole release 2.0.0, and adding the necessary flags to LIBS and CFLAGS. Run aclocal to generate the file aclocal.m4. This file will have many m4 macros, incluiding the cole m4 macro, and Run autoconf to generate the script configure. Many API calls take an argument at the end called colerrno. If it's not NULL and the call failed, it store the error code for fail, if any (if the call was successfully ended, its value is not modified).