Thanks for updating the thread.
You can find the CSS editor under X > Theme Options > CSS.
If you don't want to put CSS into Theme Options panel then you have the options of adding them in child theme. You can add the CSS codes under Appearance > Editor.
You can use following resources to download and setup child theme.
Download Child theme from following source: https://theme.co/apex/child-themes
Please take a look at following article to setup child theme: