Functionality
These are custom fields, and you want to search using the text search box? The default functionality of the S&F text search box is to search only in The Post Title and Post Content. Not any Taxonomy or Custom Fields. This reflects what WordPress does.
If you want to use free Relevanssi plugin’s search engine and cache instead of the standard WordPress textual search engine, then Relevanssi has settings that allow this. You have to enable searching of the specific taxonomy(ies) and/or the custom field(s) in Relevanssi’s settings and then build the Relevanssi cache. You have to tell S&F to use Relevanssi in the S&F form’s advanced settings. See our guide here:
https://www.designsandcode.com/documentation/search-filter-pro/3rd-party/relevanssi/
You may (some users say it works, some say not) also try the free WP Extended Search plugin to do much the same, but no special support is needed in S&F for this plugin, AFAIK.
Appearance
As to CSS, this varies considerably according to your theme. Some themes have a place to enter Custom CSS, some let you do this in the Customizer, and for some you need to manually add it using code in the child theme functions.php file, or to use a plugin. So, you might be able to go to Appearance > Customize > Additional CSS* and add the CSS, OR
you could install the Simple Custom CSS plugin and go to Appearance > Custom CSS instead.