Hello - new here so hope some kind person can help me along the way.

I've done quite a bit of trawling through this forum and have found instances that nearly match what I want to do - but not quite.

I have a village website and have been asked to put up a reminder changing every Monday morning/Sunday midnight for the forthcoming week with an image of which color refuse bin it is in the current week - ie green bin one week and black bin the next. A number of folks have already said how useful it is but the Javascript I am using currently changes the image over on Saturdays.

This is the code I am using currently:

<script type = "text/javascript">
Date.prototype.getWeek = function() {
var onejan = new Date(this.getFullYear(),0,1); // month 0 is January
addDays(2);
return Math.ceil((((this - onejan) / 86400000) + onejan.getDay()+1)/7);
}

var today = new Date();
var weekno = today.getWeek();

var images = []
images [1] = "images/green.png";
images [2] = "images/black.png";
images [3] = "images/green.png";
images [4] = "images/black.png";
images [5] = "images/green.png";
images [6] = "images/black.png";
images [7] = "images/green.png";
images [8] = "images/black.png";
images [9] = "images/green.png";
images [10] = "images/black.png";
images [11] = "images/green.png";
images [12] = "images/black.png";
images [13] = "images/green.png";
images [14] = "images/black.png";
images [15] = "images/green.png";
images [16] = "images/black.png";
images [17] = "images/green.png";
images [18] = "images/black.png";
images [19] = "images/green.png";
images [20] = "images/black.png";
images [21] = "images/green.png";
images [22] = "images/black.png";
images [23] = "images/green.png";
images [24] = "images/black.png";
images [25] = "images/green.png";
images [26] = "images/black.png";
images [27] = "images/green.png";
images [28] = "images/black.png";
images [29] = "images/green.png";
images [30] = "images/black.png";
images [31] = "images/green.png";
images [32] = "images/black.png";
images [33] = "images/green.png";
images [34] = "images/black.png";
images [35] = "images/green.png";
images [36] = "images/black.png";
images [37] = "images/green.png";
images [38] = "images/black.png";
images [39] = "images/green.png";
images [40] = "images/black.png";
images [41] = "images/green.png";
images [42] = "images/black.png";
images [43] = "images/green.png";
images [44] = "images/black.png";
images [45] = "images/green.png";
images [46] = "images/black.png";
images [47] = "images/green.png";
images [48] = "images/black.png";
images [49] = "images/green.png";
images [50] = "images/black.png";
images [51] = "images/green.png";
images [52] = "images/black.png";
images [53] = "images/green.png";


document.getElementById("myimage").src = images[weekno];

</script>

window.location = 'week'+((new Date().getWeek()+1)%2)+'.png';

and the site is here: http://www.bedstoneandbucknell.org/

I anyone can give me an idea of it's doable I'd be most grateful. Also I am a bit of a numpty so if it's also possible a simple explanation would be wonderful.

Thanks

Graham