simple parallax

parallax.css

#parallax-wrap {
	height: 400px; /* anything you want/need */
	width: 100%;
	position: relative;
	display: block;
}
.parallax {
	position:absolute;
	width:100%;
	height:100%;
	background-image: url(images/parallax.jpg);
	background-repeat: no-repeat;
	background-position:center center;
	background-attachment:fixed;
	background-size: cover;
}

parallax.html

<div id="parallax-wrap">
	<div class="parallax" data-speed="5"></div>
</div>

parallax.js

function parallaxBG(item,speed) {
  var pos = item.offset();
  $(window).scroll(function() {
    var yPos = -(($(window).scrollTop()-pos.top)/speed);
    var coords = 'center '+ yPos + 'px';
    item.css({ 'background-position': coords });
  });
}
function initParallax() {
  $('.parallax').each(function() { 
    var speed = ($(this).attr('data-speed')) ? parseInt($(this).attr('data-speed')): 10;
    parallaxBG($(this),speed); 
  });
}