https://forum.kicad.info/t/introductory-videos-on-simulation-with-ngspice-in-kicad-8/48621
https://forum.kicad.info/t/simulation-examples-for-kicad-eeschema-ngspice/34443
https://forum.kicad.info/t/simulation-examples-for-kicad8-eeschema-ngspice/45546
These maybe of help.