Adding background Image , Adding Layer.

 //OverLay. ( 1st Way )
  .parent {
       background: url("./folder1/img.jpg') no-repeat center center/cover;
  }
  .child { 
      background-color : rgba(0,0,0,0.5);
    //It will add Black ( required ) layer on the top of the parent-Background Image. 
    }       

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 //BackgroundImage, Adding Layer on the top of the Image. ( 2nd Way )
// Adding Image and providing Layer on that specific background only.
.selectContainer {
    background: linear-gradient(
        to bottom,
        rgba(0, 0, 0, 0.377),
        rgba(0,0,0, 100)
      ),url(/r/featured.jpg) no-repeat center center/cover;
}