You can use MoveWindow (Where hWnd is the window you want to move):
[DllImport("user32.dll", SetLastError = true)]
internal static extern bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);
MoveWindow(ApplicationHandle, 600, 600, 600, 600, true);
If you don't know the window pointer, you can use the FindWindow functionality.
Also worth a read is MSDN SetWindowPos (Very similar to MoveWindow).
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