Check out example codes for "insert image by css". It will help you in understanding the concepts better.

Code Example 1

.element {
  background-image: url("imageFile.png");
}

Code Example 2

<img src="img_girl.jpg" alt="Girl in a jacket" width="500" height="600">

Code Example 3

<img src="smiley.gif" alt="Smiley face" width="42" height="42" style="vertical-align:bottom">

    <img src="smiley.gif" alt="Smiley face" width="42" height="42" style="vertical-align:middle">

    <img src="smiley.gif" alt="Smiley face" width="42" height="42" style="vertical-align:top">

    <img src="smiley.gif" alt="Smiley face" width="42" height="42" style="float:right">

    <img src="smiley.gif" alt="Smiley face" width="42" height="42" style="float:left">

Code Example 4

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');
}

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