Hi Rob,
The file is normally called MySpindleDefs.h not MySpindleDefs.c. By convention files that only define common things to be included into multiple C files or programs are given .h file extensions and are referred to as "header" files. In actuality the included file can be any name with any extension as the compiler simply includes the file it was told
to include. But the name and extension must match exactly. The file to be included must also be located in a directory where the compiler has been told to look for files to include. The simplest thing is to put the file to be included into the same directory as the file that includes it.
HTH
Regards
TK