Hello Dhiman Kakati
There are various steps to follow. I hope this will help you.
Double click on the final results file whose file name has the last iteration number.
Select Power Sweep Analysis under tools menu. Power Sweep Viewer appears.
The data can be selected from the top Drop-down list menu.
Select Power Spectrum on Observation line
Select/unselect the swept parameter from the left side list to display/un-display the corresponding power spectrum.
Click on the icon on the up-left corner in graph to check the graph tools and displayed data operation.
Thanks