make background overlay css
#element-with-background-image {
position: relative;
background-image: url("//spin.atomicobject.com/wp-content/uploads/20170324102432/portfolio-tips-feature-image.jpg");
}
#color-overlay {
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-color: black;
opacity: 0.6;
}