How to Hook Readfile,help me! REPOST

CAPIHook g_ReadFile; //the main object of CAPIHook! 
typedef bool (WINAPI *PFNReadFile)( 
__in          HANDLE hFile, 
__out        LPVOID lpBuffer, 
__in          DWORD nNumberOfBytesToRea 
  __out        LPDWORD lpNumberOfBytesRead 
  __in          LPOVERLAPPED lpOverlapped  ); 
bool WINAPI MyReadFile(  
  __in          HANDLE hFile, 
  __out        LPVOID lpBuffer, 
  __in          DWORD nNumberOfBytesToRead, 
  __out        LPDWORD lpNumberOfBytesRead, 
  __in          LPOVERLAPPED lpOverlapped    ) 
{ 
char * m_pBuf = (char *)"zxcvzxcv";  //The problem is here, how to write my own data into the Buffer, displayed it out?
DWORD len = 0;
nResult = ((PFNReadFile)(PROC)g_ReadFile)(hFile, m_pBuf, strlen(m_pBuf), &len, NULL); 
return nResult; 
}