Adding buttons forward and slide back

Question

Galera made a code java script that changes the background-image of my <header> on the site however would like to know if it gives to add cursor of next(>) and Previous(<) to change the images when you click on them already this changing automata more would like to implement this option.

JS:

var images=new Array('img/bg-header.jpg','img/bg-header-2.jpg');
var nextimage=0;
doSlideshow();

function doSlideshow(){
    if(nextimage>=images.length){nextimage=0;}
    $('.header')
        .css('background-image','url("'+images[nextimage++]+'")')
        .fadeIn(100,function(){
            setTimeout(doSlideshow,4000);
        });
}