Adding Rotating images

[TheUpcycledMarket]

I would like to add a rotating image on my website in the area to the right under my "BE SOCIAL" section. http://theupcycledmarket.com

I have my images uploaded to my theme (Vintage) and I have copied a JavaScript code from a help website (where I would change the image names to mine and change the sizes of the images). It says to copy and paste the below code into my header. Where would my header be located. And would I be missing anything else?
It also says to: Figure out where you want the images to appear on the page and copy in:
<layer id="placeholderlayer"></layer><div id="placeholderdiv"></div> ---------> Where would I put this? And do I need to change anything in the ^^^ above code?
***************************************

<script language="JavaScript1.2">

var howOften = 5; //number often in seconds to rotate
var current = 0; //start the counter at 0
var ns6 = document.getElementById&&!document.all; //detect netscape 6

// place your images, text, etc in the array elements here
var items = new Array();
items[0]="<a href='link.htm' ><img alt='image0 (9K)' src=' /Images/image0.jpg' height='300' width='300' border='0' /></a>"; //a linked image
items[1]="<a href='link.htm'><img alt='image1 (9K)' src='/Images/image1.jpg' height='300' width='300' border='0' /></a>"; //a linked image
items[2]="<a href='link.htm'><img alt='image2 (9K)' src='/Images/image2.jpg' height='300' width='300' border='0' /></a>"; //a linked image
items[3]="<a href='link.htm'><img alt='image3 (9K)' src='/Images/image3.jpg' height='300' width='300' border='0' /></a>"; //a linked image
items[4]="<a href='link.htm'><img alt='image4 (9K)' src='/Images/image4.jpg' height='300' width='300' border='0' /></a>"; //a linked image
items[5]="<a href='link.htm'><img alt='image5 (18K)' src='/Images/image5.jpg' height='300' width='300' border='0' /></a>"; //a linked image
function rotater() {
document.getElementById("placeholder").innerHTML = items[current];
current = (current==items.length-1) ? 0 : current + 1;
setTimeout("rotater()",howOften*1000);
}

function rotater() {
if(document.layers) {
document.placeholderlayer.document.write(items[current]);
document.placeholderlayer.document.close();
}
if(ns6)document.getElementById("placeholderdiv").i nnerHTML=items[current]
if(document.all)
placeholderdiv.innerHTML=items[current];

current = (current==items.length-1) ? 0 : current + 1; //increment or reset
setTimeout("rotater()",howOften*1000);
}
window.onload=rotater;
//-->
</script>