drawing dots and learning win prog

Hi, In the book Programming for Windows by Charles Petzold I found code for drawing sinusoide using Polyline() function. However I need to draw a discrete sinusoide (I'm writing application that will simulate signal's sampling)
I manage to this making small changes

Code:

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#include <windows.h>
#include <math.h>

#define NUM    200
#define TWOPI  (2 * 3.14159)

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
    static TCHAR szAppName[] = TEXT ("SineWave") ;
    HWND        hwnd ;
    MSG          msg ;
    WNDCLASS    wndclass ;
   
    wndclass.style        = CS_HREDRAW | CS_VREDRAW ;
    wndclass.lpfnWndProc  = WndProc ;
    wndclass.cbClsExtra    = 0 ;
    wndclass.cbWndExtra    = 0 ;
    wndclass.hInstance    = hInstance ;
    wndclass.hIcon        = LoadIcon (NULL, IDI_APPLICATION) ;
    wndclass.hCursor      = LoadCursor (NULL, IDC_ARROW) ;
    wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
    wndclass.lpszMenuName  = NULL ;
    wndclass.lpszClassName = szAppName ;
         
    if (!RegisterClass (&wndclass))
    {
          MessageBox (NULL, TEXT ("Program requires Windows NT!"),
                      szAppName, MB_ICONERROR) ;
          return 0 ;
    }
   
    hwnd = CreateWindow (szAppName, TEXT ("Sine Wave Using Polyline"),
                          WS_OVERLAPPEDWINDOW,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          NULL, NULL, hInstance, NULL) ;

    ShowWindow (hwnd, iCmdShow) ;
    UpdateWindow (hwnd) ;
   
    while (GetMessage (&msg, NULL, 0, 0))
    {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
    }
    return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static int  cxClient, cyClient ;
    HDC        hdc ;
    int        i ;
    PAINTSTRUCT ps ;
    POINT      apt [NUM] ;
    int k,p,X,Y;
    switch (message)
    {
    case WM_SIZE:
          cxClient = LOWORD (lParam) ;
          cyClient = HIWORD (lParam) ;
          return 0 ;
         
    case WM_PAINT:
               
          hdc = BeginPaint (hwnd, &ps) ;
         
          MoveToEx (hdc, 0,        cyClient / 2, NULL) ;
          LineTo  (hdc, cxClient, cyClient / 2) ;
                 
                 
          for (i = 0 ; i < NUM ; i++)
          {
              apt[i].x = i * cxClient / NUM ;
              apt[i].y = (int) (cyClient / 2 * (1 - sin (TWOPI * i / NUM))) ;
                         
                          //My approach
                         
                          Y=apt[i].y;
                         
                          for(k=0;k<3;k++,Y++)
                          {
                                  X=apt[i].x;
                                  for(p=0;p<3;p++,X++)
                                          SetPixel(hdc,X,Y,RGB(255,0,0));
                          }
                         
          }
         
          //Polyline (hdc, apt, NUM) ;
          return 0 ;
         
    case WM_DESTROY:
          PostQuitMessage (0) ;
          return 0 ;
    }
    return DefWindowProc (hwnd, message, wParam, lParam) ;
}

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I was wondering if there any better method to draw point (it should be thicker then one pixel)!

Another thing I would like to ask is how much time did you spend lerning windows programming?
I didn't have any experience with windows programming before and when I started reading Petzold's book I found this is more harder then I expected because of so many system calls and a lot of functions! Maybe I should read some other book first before Petzolds?
Thanks for help!