I have a ngspice netlist, how can I simulate it and see the plotting? I am just very new to kicad, thanks
Have you read the manual ? http://docs.kicad-pcb.org/5.1.2/en/eeschema/eeschema.html#simulator
This was moved to the “Simulation (Ngspice)” category. It might get better visibility from those interested in the topic.
A ngspice netlist is not a valid input to KiCAD. Use standard ngspice instead.
You also might be interested in running the tutorial examples in http://ngspice.sourceforge.net/ngspice-eeschema.html to learn about ngspice in KiCad Eeschema.