For an example-based introduction to using ODBC from C, refer to the Easysoft tutorial ODBC from C tutorial (part 1) — getting started.
Easysoft also recommend that you refer to the ODBC Programmer's Reference and other ODBC documentation provided on the Microsoft web site.
A full Easysoft ODBC-ODBC Bridge installation includes some example ODBC applications written in C, PHP, and Perl, which are located in the ODBC-ODBC Bridge examples
subdirectory.