how to add an overlay box in html css code example

Example: 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;
}