Edit in JSFiddle

$("#move-right-button").click(function(){
	$("#move-box").animate({
		left: "+=20px"
	});
});

$("#move-left-button").click(function(){
	$("#move-box").animate({
		left: "-=20px"
	});
});
#move-box{
	width: 100px;
	height: 100px;
	background-color: black;
	position: relative; 
}
<div id="move-box"></div>
<button type="button" id="move-left-button">&laquo;</button>
<button type="button" id="move-right-button">&raquo;</button>