WSJT X automatically opens the log dialog (if set properly in the setup menu.) You can turn the automatic pop-up for the log off or on. If you turn it on, you won't have to click "LOG QSO." The dialog box will open when 73 is sent. In the WSJT X menu go to file, settings, open log directory and observe the ADI File name. The file is in ADIF format. You should be able to figure out what to do from that point.