u will need something more than plain html, something like javascript. Hope this works for you:
<body onload="changePic();">
<script type="text/javascript">
var imgArray = new Array();
imgArray[0]="a.jpg";
imgArray[1]="b.jpg";
imgArray[2]="c.jpg";
imgArray[3]="d.jpg";
imgArray[4]="e.jpg";
imgArray[5]="f.jpg";
var sec=5;
var time;
var i=1;
function changePic(){
sec = sec - 1;
time=setTimeout("changePic()",1000);
if (sec==0){
document.getElementById('imageFrame').src=imgArray[i];
sec=5;
if(i==imgArray.length){
i=0;}
else{
i++;}
}
}
</script>
<img id="imageFrame" src="a.jpg" />