Alessio18911,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
.page {
position: relative;
width: 400px;
height: 250px;
outline: 1px solid orange;
background-size: cover;
background-repeat: no-repeat;
}
.bg1 {
background-image: url("http://hd4desktop.online/images/m/a-squirrel-408002.jpg");
}
.bg2 {
background-image: url("http://www.nicefotos.ru/img/picture/May/30/f5cc5821bbc50c0920bc86fa65d9cb4c/mini_1.jpg");
}
.bg3 {
background-image: url("http://cybercomnet.fr/www/wallpaper/_data/i/galleries/Animaux/Lapin/Lapin-8-cu_s9999x200.jpg");
}
.radio-controls {
position: absolute;
bottom: 0;
left: 50%;
margin-left: -55px;
width: 110px;
height: 50px;
text-align: center;
line-height: 65px;
outline: 1px solid red;
}
label {
display: inline-block;
width: 20px;
height: 20px;
background-color: dodgerblue;
background-clip: padding-box;
border: 5px solid transparent;
border-radius: 50%;
box-shadow: 0 0 2px 1px dodgerblue;
}
</style>
<script>
window.addEventListener('DOMContentLoaded', function() {
var page = document.querySelector('.page'),
label = page.querySelectorAll('label');
[].forEach.call(label, function(item, i) {
item.addEventListener('click', function() {
page.className = "page bg"+ (i+1)
});
});
});
</script>
</head>
<body>
<div class="page bg1">
<div class="radio-controls">
<label class="label" for="radio1"></label>
<label class="label" for="radio2"></label>
<label class="label" for="radio3"></label>
</div>
</div>
</body>
</html>