You can find the CSS to make your customizations for the Front Page #2 widget on line 1569 (in the style.css file).
You can change the background color directly from the CSS –
.front-page-2 .image-section {
background: #fa5738;
padding: 60px 0 20px;
}
Or you could use the Customizer to change the color, but that changes the default theme color for the whole site (links, background, etc)
Line 1569 – 1604 covers the front page 2 widget CSS. If you’re using a 3rd party plugin then you’ll have to come up with some custom code if you want to customize how it displays on the site.