Cropping a BitMap.

I am writting a program and need help.
My program is suppose to take a screen shot and make it a bitmap, call it oldmap. I than would like to crop oldmap from its center with a size of 200 by 200 or 50 by 50 or whatever the user would like, and call it newmap.
I would than like to delete the oldmap and place it with the new map. I am confused on how to implement it.
Here is my code.

Code:

---

//////////////
bool Capture::screenshotGDI(Screenshot &screeny)
{
        HWND hwnd = FindWindowA(0, WindowName);
        if (hwnd == NULL)
        {
                cout << "ERROR: HWND not found!" << endl;
                return false;
        }

        int sWidth = GetSystemMetrics(SM_CXSCREEN);
        int sHeight = GetSystemMetrics(SM_CYSCREEN);

        HDC hdc = GetDC(0);
        HDC captureDC = CreateCompatibleDC(hdc);
        HBITMAP hBmp = CreateCompatibleBitmap(hdc, sWidth, sHeight);
        HGDIOBJ hOld = SelectObject(captureDC, hBmp);
       
        if (!BitBlt(captureDC, 0, 0, sWidth, sHeight, hdc, 0, 0, SRCCOPY | CAPTUREBLT))
        {
                cout << "ERROR: bit-block transfer failed!" << endl;
                release(hwnd, hdc, captureDC, hBmp);
                return false;
        }

        SelectObject(captureDC, hBmp);

        BITMAPINFO bmpInfo = { 0 };
        bmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
        if (!GetDIBits(hdc, hBmp, 0, 0, NULL, &bmpInfo, DIB_RGB_COLORS)) //get bmpInfo
        {
                cout << "ERROR: Failed to get Bitmap Info." << endl;
                release(hwnd, hdc, captureDC, hBmp);
                return false;
        }
        bmpInfo.bmiHeader.biCompression = BI_RGB;

        screeny.FreeMemory();

        int pixNo = bmpInfo.bmiHeader.biWidth *  bmpInfo.bmiHeader.biHeight;
        screeny.pixels = new RGBQUAD[pixNo];
        if (!screeny.pixels)
        {
                cout << "ERROR: Failed allocating RGBQUAD[" << pixNo << "]" << endl;
                release(hwnd, hdc, captureDC, hBmp);
                return false;
        }

        if (!GetDIBits(hdc, hBmp, 0, bmpInfo.bmiHeader.biHeight, (LPVOID)screeny.pixels, &bmpInfo, DIB_RGB_COLORS))
        {
                cout << "ERROR: Getting the bitmap buffer!" << endl;
                screeny.FreeMemory();
                release(hwnd, hdc, captureDC, hBmp);
                return false;
        }

        screeny.width = bmpInfo.bmiHeader.biWidth;
        screeny.height = bmpInfo.bmiHeader.biHeight;
        screeny.length = pixNo;

        release(hwnd, hdc, captureDC, hBmp);
        return true;
}
//////////////////

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Any help on implementing what was stated would be amazing.
Thank you in advance.

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[Thread moved from non-visual c++ issues as relating to use of Windows APIs.]

BitBlt(targetDC, x, y, width, height, sourceDC, ...) is what they call cropping. Start thinking from this point.