Changing Process Bytes

foo()
{
    HWND hWnd;
    while((hWnd = FindWindow(null, "Untitled - Notepad")) == NULL) // Keep waiting for a window with 'Untitled - Notepad' to appear
        Sleep(100);

    DWORD pID;
    GetWindowThreadProcessId(hWnd, &pID); // Get the process ID from the window handle
    HANDLE pHandle = OpenProcess(PROCESS_VM_WRITE, FALSE, pID);
    if(pHandle == NULL)
        return; // Couldn't get a process handle.

    // Replace 0xDEADBEEF with the real address and replace the 5 with the real byte array size.
    BYTE[] data = { 0x00, 0x11, 0x55, 0x10, 0x42 };
    WriteProcessMemory(pHandle, (LPVOID)0xDEADBEEF, &data, 5, NULL);

    CloseHandle(pHandle); // Close the handle if we don't need it anymore.
}