Adding a background color to blocks and sections of website

Site URL: https://blockpaperprint.com

Hello everyone!
How can I change the background color for specific parts of my website and blocks? 
For example, on my homepage, I'm listing packages, which I'd like to highlight with blue and black backgrounds. In the case study section, I'd like to have a grey background. 
Your input would be of great value and appreciation! 
I've attached an image mockup for reference, in addition to my website,. 

Thanks again!

Charles

You need to use CSS to do this

With above box in screenshot, Add to Home > Design > Custom CSS

div#block-yui_3_17_2_1_1580839942134_161965 {
    background: grey;
    padding-top: 0;
    padding-left: 0;
    padding-right: 0;
}
div#block-yui_3_17_2_1_1580839942134_161965 h2 {
    background: blue;
    text-align: center;
}