Hello DeekPark,
After you have installed NI-DAQ you can use the "nidaq.h" header file located in the C:\Program Files\National Instruments\NI-DAQ\Include. Also, the library file, "nidaq32.lib" is located in C:\Program Files\National Instruments\NI-DAQ\Lib. If you wish to call the dll functions directly the DLL is "nidaq32.dll" located in C:\WINDOWS\system32.
I hope this helps get you started, and have a great weekend!
Brooks