Answers for "how to choose a image to put on the background css"

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>

add background image in css

.w {
background-image: url("images/tom1.png");
}

.a {
background-image: url("images/tom2.png");
}

.s {
background-image: url("images/tom3.png");
}