Answers for "how to set background image for entire website using css"

css background image

background-image: url("image.png");
background-position: center;
background-repeat: no-repeat;
background-size: cover;

background image size css

#example1 {
  background: url(mountain.jpg);
  background-repeat: no-repeat;
  background-size: auto;
}

#example2 {
  background: url(mountain.jpg);
  background-repeat: no-repeat;
  background-size: 300px 100px;
}

How to set a image as a backgroung image

<style>
body {
  background-image: url('img_girl.jpg');
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: cover;
}
</style>