This code snippet will let you control the move along the queue of songs.
/* Instantiate the global sp object; include models */
var sp = getSpotifyApi(1);
var models = sp.require("sp://import/scripts/api/models");
var player = models.player;
$('#previous').click(function(){
player.previous();
});
$('#next').click(function(){
player.next();
});
<input type="button" id="previous" value="« Previous" />
<input type="button" id="next" value="Next »" />