void Append(const LPBYTE lpData, DWORD len);
void Append(LPCTSTR lpData);
to append
  Property Description  
    Method Name Append  
    Argument - lpData A pointer to the data to be appended  
    Argument - len The number of bytes from lpData to append  
    Argument - lpData A string to append to the end of the collection  
    Description Appends the data to the end of the existing data held in the class  
    Remarks If the build is UNICODE then 2 bytes per char are used when when converting strings, if not then just the one.