If your version of fldigi is like my ver4.0.1 on Linux, it is very straightforward:
From menu Configure --> Miscellaneous --> Spotting
Mark the check boxes as to your preference
Set the host to
report.pskreporter.info and the port to 4739
Initialize button if you've made a change.
At that point the Spot button at the top right of your main screen should be active -- toggle it by clicking, green on gray is off.
Once this is set up you can also manually spot a station if the call sign is in the Call box under Frq, but right clicking the world-globe/QRZ button that's between the two frequency displays.
I hope I'm not being obtuse and missing your entire question...