Save wave file using waveInOpen

I am trying to record sound in a .wave file using waveInOpen and co ( see here )

Here is my code to write to the buffer and it seems to work:

#include <Windows.h>
#include <MMSystem.h>
#include <iostream>

using namespace std;

int main(){

    HWAVEIN microHandle;
    WAVEHDR waveHeader;

    const int NUMPTS = 22050 * 10;   // 10 seconds
    int sampleRate = 22050;
    short int waveIn[NUMPTS];   // 'short int' is a 16-bit type; I request 16-bit samples below
                                // for 8-bit capture, you'd use 'unsigned char' or 'BYTE' 8-bit types

    MMRESULT result = 0;

    WAVEFORMATEX format;
    format.wFormatTag=WAVE_FORMAT_PCM;      // simple, uncompressed format
    format.wBitsPerSample=8;                //  16 for high quality, 8 for telephone-grade
    format.nChannels=1;                     //  1=mono, 2=stereo
    format.nSamplesPerSec=sampleRate;       //  22050
    format.nAvgBytesPerSec=format.nSamplesPerSec*format.nChannels*format.wBitsPerSample/8;
                                            // = nSamplesPerSec * n.Channels * wBitsPerSample/8
    format.nBlockAlign=format.nChannels*format.wBitsPerSample/8;                    
                                            // = n.Channels * wBitsPerSample/8
    format.cbSize=0;

    result = waveInOpen(&microHandle, WAVE_MAPPER, &format, 0L, 0L, WAVE_FORMAT_DIRECT);

    if (result)
    {
        cout << "Fail step 1" << endl;
        cout << result << endl;
        Sleep(10000);
        return 0; 
    }

    // Set up and prepare header for input
    waveHeader.lpData = (LPSTR)waveIn;
    waveHeader.dwBufferLength = NUMPTS*2;
    waveHeader.dwBytesRecorded=0;
    waveHeader.dwUser = 0L;
    waveHeader.dwFlags = 0L;
    waveHeader.dwLoops = 0L;
    waveInPrepareHeader(microHandle, &waveHeader, sizeof(WAVEHDR));

    // Insert a wave input buffer
    result = waveInAddBuffer(microHandle, &waveHeader, sizeof(WAVEHDR));

    if (result)
    {
        cout << "Fail step 2" << endl;
        cout << result << endl;
        Sleep(10000);
        return 0;
    }

    result = waveInStart(microHandle);

    if (result)
    {
        cout << "Fail step 3" << endl;
        cout << result << endl;
        Sleep(10000);
        return 0;
    }

     // Wait until finished recording
     do {} while (waveInUnprepareHeader(microHandle, &waveHeader, sizeof(WAVEHDR))==WAVERR_STILLPLAYING);

     waveInClose(microHandle);

    return 0;
}

But I did not find any function or explanation on how to save it to disk

Should I keep the WAVEFORMATEX structure? or are there other things to add to the header of the wave file?

The only thing that I should use only Windows libraries, I can not install any other

Thank:)