Calibration in Qt, pls Help

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good afternoon, I'm trying to calibrate my camera (usb - webcam) with these instructions: http://docs.opencv.org/doc/tutorials/calib3d/camera_calibration/camera_calibration.html, I'm working on Qt 4.8.3 (32 bit), but I do not really understand English, so I miss some steps or do not quite understand. This is why I would ask if you can post the basic steps to calibrate my camera.

thanks, I'll wait for your answers.