Migrating from JoomlaShine - Suggestions on module CSS

A few days ago I purchased your Developer License with the intent of recreating several websites that I currently host that use templates from JoomlaShine. I am becoming familiar with your SP Page Builder and like what I see, but I am not clear on how to handle the formatting of modules in left/right columns that are assigned to the Helix positions but not directly edited in SP Page Builder. One of my reference websites is located at https://darkskymissouri.org/. My guess is that I need to add custom css code to the template to achieve the left/right module boxing. JoomlaShine had a CSS wizard that took care of this formatting but I am not sure how to add custom css to replicate this look. If I can get past this issue, I think your template/page builder will work for me. Can you assist?