How to make icons like iCloud?

Does anybody know how to make this really easy? I'm a starter and would like to have 3 icons on my website to make a icloud-based website for a task on school. I just don't really know how to do it, I already did some research but I didn't find anything. Inspect element is a bit to hard to understand yet... Any help is welcome!

iCloud Exemple

Solution

This would be a start for your homework :)

body {
  background: red;
  /* For browsers that do not support gradients */
  background: -webkit-linear-gradient(left top, red, yellow);
  /* For Safari     5.1 to 6.0 */
  background: -o-linear-gradient(bottom right, red, yellow);
  /* For Opera 11.1     to 12.0 */
  background: -moz-linear-gradient(bottom right, red, yellow);
  /* For Firefox 3.6 to 15 */
  background: linear-gradient(to bottom right, red, yellow);
  /* Standard syntax */
}

div.one,
div.two,
div.three {
  float: left;
  width: 200px;
  height: 200px;
  background-color: white;
  border-radius: 12px;
  margin: 20px;
  text-align: center;
}

<div class="one">Some text</div>
<div class="two">Some text</div>
<div class="three">Some text</div>