This is the prototype of the function:
HRESULT ExcelRpt_WorkbookOpen (CAObjHandle applicationHandle, char filename[], CAObjHandle *workbookHandle);
You pass the application handle and the file path as the first 2 parameters, function opens the file and outputs its handle as the last parameter.
You will use this handle for any operation you do over that file.
Hope this helps,
S. Eren BALCI
IMESTEK