First write out the html structure

<div class="scrollable">
	<div id="par_1">
		<div class="par_nav">
			<ul>
				<li><a href="#par_1">Parallax Section 1</a></li>
				<li><a href="#par_2">Parallax Section 2</a></li>
				<li><a href="#par_3">Parallax Section 3</a></li>
			</ul>
		</div>
	</div>
	<div id="par_2">
		<div class="par_nav">
			<ul>
				<li><a href="#par_1" class="top">Top</a></li>
					</ul>
		</div>
	</div>
	<div id="par_3">
		<div class="par_nav">
			<ul>
				<li><a href="#par_1" class="top">Top</a></li>
			</ul>
		</div>
	</div>
</div>
  						

Next create your parallax javascript file

// JavaScript Document

// for animating down to the sections...
$('.par_nav a').click(function(){

	var theTarget = $(this).attr('href');
	
	$(theTarget).animatescroll({element:'.scrollable'});	
	
});

// for animating back up to the top of the section
$('.top').click(function(){

	var theTarget = $(this).attr('href');
	
	$(theTarget).animatescroll({element:'.scrollable'});	
	
});

Because this particular parralax in a separate scrollable window, and additional javascript file needs to be created. It's a javascript file that's quite long and can be obtained on line at github.com/ramswaroop/animatescroll.js/

/* Coded by Ramswaroop */
(function(e){e.easing["jswing"]=e.easing["swing"];e.extend(e.easing,{def:"easeOutQuad",swing:function(t,n,r,i,s){return e.easing[e.easing.def](t,n,r,i,s)},easeInQuad:function(e,t,n,r,i){return r*(t/=i)*t+n},easeOutQuad:function(e,t,n,r,i){return-r*(t/=i)*(t-2)+n},easeInOutQuad:function(e,t,n,r,i){if((t/=i/2)<1)return r/2*t*t+n;return-r/2*(--t*(t-2)-1)+n},easeInCubic:function(e,t,n,r,i){return r*(t/=i)*t*t+n},easeOutCubic:function(e,t,n,r,i){return r*((t=t/i-1)*t*t+1)+n},easeInOutCubic:function(e,t,n,r,i){if((t/=i/2)<1)return r/2*t*t*t+n;return r/2*((t-=2)*t*t+2)+n},easeInQuart:function(e,t,n,r,i){return r*(t/=i)*t*t*t+n},easeOutQuart:function(e,t,n,r,i){return-r*((t=t/i-1)*t*t*t-1)+n},easeInOutQuart:function(e,t,n,r,i){if((t/=i/2)<1)return r/2*t*t*t*t+n;return-r/2*((t-=2)*t*t*t-2)+n},easeInQuint:function(e,t,n,r,i){return r*(t/=i)*t*t*t*t+n},easeOutQuint:function(e,t,n,r,i){return r*((t=t/i-1)*t*t*t*t+1)+n},easeInOutQuint:function(e,t,n,r,i){if((t/=i/2)<1)return r/2*t*t*t*t*t+n;return r/2*((t-=2)*t*t*t*t+2)+n},easeInSine:function(e,t,n,r,i){return-r*Math.cos(t/i*(Math.PI/2))+r+n},easeOutSine:function(e,t,n,r,i){return r*Math.sin(t/i*(Math.PI/2))+n},easeInOutSine:function(e,t,n,r,i){return-r/2*(Math.cos(Math.PI*t/i)-1)+n},easeInExpo:function(e,t,n,r,i){return t==0?n:r*Math.pow(2,10*(t/i-1))+n},easeOutExpo:function(e,t,n,r,i){return t==i?n+r:r*(-Math.pow(2,-10*t/i)+1)+n},easeInOutExpo:function(e,t,n,r,i){if(t==0)return n;if(t==i)return n+r;if((t/=i/2)<1)return r/2*Math.pow(2,10*(t-1))+n;return r/2*(-Math.pow(2,-10*--t)+2)+n},easeInCirc:function(e,t,n,r,i){return-r*(Math.sqrt(1-(t/=i)*t)-1)+n},easeOutCirc:function(e,t,n,r,i){return r*Math.sqrt(1-(t=t/i-1)*t)+n},easeInOutCirc:function(e,t,n,r,i){if((t/=i/2)<1)return-r/2*(Math.sqrt(1-t*t)-1)+n;return r/2*(Math.sqrt(1-(t-=2)*t)+1)+n},easeInElastic:function(e,t,n,r,i){var s=1.70158;var o=0;var u=r;if(t==0)return n;if((t/=i)==1)return n+r;if(!o)o=i*.3;if(u<Math.abs(r)){u=r;var s=o/4}else var s=o/(2*Math.PI)*Math.asin(r/u);return-(u*Math.pow(2,10*(t-=1))*Math.sin((t*i-s)*2*Math.PI/o))+n},easeOutElastic:function(e,t,n,r,i){var s=1.70158;var o=0;var u=r;if(t==0)return n;if((t/=i)==1)return n+r;if(!o)o=i*.3;if(u<Math.abs(r)){u=r;var s=o/4}else var s=o/(2*Math.PI)*Math.asin(r/u);return u*Math.pow(2,-10*t)*Math.sin((t*i-s)*2*Math.PI/o)+r+n},easeInOutElastic:function(e,t,n,r,i){var s=1.70158;var o=0;var u=r;if(t==0)return n;if((t/=i/2)==2)return n+r;if(!o)o=i*.3*1.5;if(u<Math.abs(r)){u=r;var s=o/4}else var s=o/(2*Math.PI)*Math.asin(r/u);if(t<1)return-.5*u*Math.pow(2,10*(t-=1))*Math.sin((t*i-s)*2*Math.PI/o)+n;return u*Math.pow(2,-10*(t-=1))*Math.sin((t*i-s)*2*Math.PI/o)*.5+r+n},easeInBack:function(e,t,n,r,i,s){if(s==undefined)s=1.70158;return r*(t/=i)*t*((s+1)*t-s)+n},easeOutBack:function(e,t,n,r,i,s){if(s==undefined)s=1.70158;return r*((t=t/i-1)*t*((s+1)*t+s)+1)+n},easeInOutBack:function(e,t,n,r,i,s){if(s==undefined)s=1.70158;if((t/=i/2)<1)return r/2*t*t*(((s*=1.525)+1)*t-s)+n;return r/2*((t-=2)*t*(((s*=1.525)+1)*t+s)+2)+n},easeInBounce:function(t,n,r,i,s){return i-e.easing.easeOutBounce(t,s-n,0,i,s)+r},easeOutBounce:function(e,t,n,r,i){if((t/=i)<1/2.75){return r*7.5625*t*t+n}else if(t<2/2.75){return r*(7.5625*(t-=1.5/2.75)*t+.75)+n}else if(t<2.5/2.75){return r*(7.5625*(t-=2.25/2.75)*t+.9375)+n}else{return r*(7.5625*(t-=2.625/2.75)*t+.984375)+n}},easeInOutBounce:function(t,n,r,i,s){if(n<s/2)return e.easing.easeInBounce(t,n*2,0,i,s)*.5+r;return e.easing.easeOutBounce(t,n*2-s,0,i,s)*.5+i*.5+r}});e.fn.animatescroll=function(t){var n=e.extend({},e.fn.animatescroll.defaults,t);if(typeof n.onScrollStart=="function"){n.onScrollStart.call(this)}if(n.element=="html,body"){var r=this.offset().top;e(n.element).stop().animate({scrollTop:r-n.padding},n.scrollSpeed,n.easing)}else{e(n.element).stop().animate({scrollTop:this.offset().top-this.parent().offset().top+this.parent().scrollTop()-n.padding},n.scrollSpeed,n.easing)}setTimeout(function(){if(typeof n.onScrollEnd=="function"){n.onScrollEnd.call(this)}},n.scrollSpeed)};e.fn.animatescroll.defaults={easing:"swing",scrollSpeed:800,padding:0,element:"html,body"}})(jQuery)

Lastly, attach your javascript files to your page

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script src="js/animatescroll.min.js"></script>
<script src="js/parallax.js"></script>