Adding content divs (Unite theme)

I am very new at customizing themes so bare with me on this one. I am trying to make adjustments to the Unite theme (Which has Bootstrap). As I’ve never tweaked a responsive template, I assume many of the attributes I want to adjust will have to be in a backup/child boot.min.css file and uploaded to the server.

I’m trying to give just the body content a background color, which I have done but other elements sharing the ‘container’ class are affected as well, so when trying to change the class of the elements sharing the ‘container’ class, the nav bar shifts and the very top bar goes black and shifts over to the left.

I thought this would be pretty basic stuff. Changing ID’s and classes.

Here is the site as it is: https://witzelsuchttapes.com/sites/blackandyellow/

Top half is supposed to be clear, nav bar as it is, and the footer straight orange. Such a learning curve with this bootstrap stuff!