Edit in JSFiddle

<h2>
BLOGIT.VN
</h2>
<div class="div1">
DIV 1
</div>
<div class="div2">
DIV 2
</div>
.div1{
    position: relative;
    z-index: 1;
    background-color: #f00;
    left: 50px;
    top: 50px;
    width: 200px;
    height: 200px;
}

.div2{
  position: relative;
  z-index: 2;
  background-color: #0f0;
  left: 100px;
  top: -100px;
  width: 200px;
  height: 200px;
}