[HUEMAN] Full width site resolved

Dear Hueman users,

I would like to make my website full width (www.Obiektywizm.pl), but maybe I don’t understand previous solutions and am too bad in CSS.

In one of threads here Author (thank you!) (https://ww.wp.xz.cn/support/topic/make-hueman-theme-full-width-1?replies=3) suggested to use
.container { padding: 0!important; }
but I tried to add this code in few places, but never it worked. Where exactly should I put it and how to apply Theme Options?

Another thread (https://ww.wp.xz.cn/support/topic/full-width-page-template-4?replies=5) suggested to use fullwidth.php, but I even have less idea how.

Could you explain dummy?
Thank you,
Tomek