Edit in JSFiddle

$(document).ready(function(){
  //.parallax(横の位置, 高さの調整, 動かす大きさ);
  $('#first').parallax("0", 3900, 0.1);
  $('#second').parallax("0", 7900, 0.1);
})

<div id="first" class="slide">
  <div class="box">
    テストその1って感じ
  </div>
</div>

<div id="second" class="slide">
  <div class="box">
    テストその2って感じ
  </div>
</div>

#first{
  background:url(http://newyear.opdsgn.com/images/bg2.png) no-repeat fixed #EC4354;
 	color: white;
	background-size: cover;
	-webkit-background-size: cover;
	-moz-background-size: cover;
	-o-background-size: cover;
	height: 3900px;
  position: relative;
}

#second{
  background:url(http://newyear.opdsgn.com/images/serious.png) no-repeat fixed #fff;
 	color: white;
	background-size: cover;
	-webkit-background-size: cover;
	-moz-background-size: cover;
	-o-background-size: cover;
  height:3000px;
  position: relative;
}

.box{
  float:right;
  position: absolute;
  right:100px;
  top:50%;
  background:#000;
  padding:20px;
}