Hello,
Please https://vc.wpbakery.com/video-academy/work-tabs-accordions-tours-visual-composer-wordpress/ As about css it depends on what you want to achieve, you can put your css code in Theme Options > Custom css, in Custom css for page http://prntscr.com/en47di or for elements http://prntscr.com/en48qv. https://developers.google.com/web/tools/chrome-devtools/iterate/inspect-styles/
Regards, Rose Tyler.
