Answers for "how to import an image css"

import image css

background-image: url(path);
background-repeat: no-repeat;

insert image by css

div.mydiv:after {
  content: url(image.jpg); /*url of your image*/
}

or

div.mydiv {
   width:100px; /*width of your image*/
   height:100px; /*height of your image*/
   background-image:url('image.file');
}