First, simply connect the PH probe.
Following this you need to run the calibration routine from the Profilux head unit (you cannot do this from the PC software).
On the head unit press the "Ph" button and scroll to "Calibration".
Set your values for the Ph Solutions you are using to Calibrate (usually 7.0 and 9.0), set your tolerance (1 being the most sensitive) and continue.
The Profilux will prompt you to place the probe in the appropriate solution, then beep when it is done.
Hope that helps!