How to do Parallax backgrounds with "Spirit Theme?"

I've seen hundreds of websites utilizing parallax backgrounds and I've used them with wordpress with a different theme (one where parallax was a simple drop-down option when adding a background into a region). I'm really hoping for some guidance on doing just a simple parallax background for separate regions.

My example would be this:
I created this page a few weeks ago, but it contains the parallax background on a few regions there. The photo of the city and the family photos collage are the examples of parallax backgrounds that I want to be able to achieve while using the wpmudev membership plugins and themes. I know that the capability is there with css, but I'm not sure how to code css yet, barely starting to learn about it.
With this cpamine site, I used a plugin and theme called WP Profit Builder, a simple drag and drop site builder as well.

How can I achieve this? :\

Mario Salazar