// in HEAD so loaded by the time function is called (if onLoad added to BODY then function runs once and first pic displayed is pic 2)

var myPic = new Array("img/after01.jpg","img/after02.jpg","img/after03.jpg","img/after04.jpg","img/after05.jpg","img/after06.jpg","img/after07.jpg","img/after08.jpg","img/after09.jpg","img/after10.jpg","img/after11.jpg","img/after12.jpg","img/after13.jpg","img/after14.jpg")
var picNumber = 1
var noOfPics = myPic.length

function previousPicture(){
    if (picNumber > 1){
    picNumber--
    }
document.after.src=myPic[picNumber-1]    // -1 because array starts at 0 so picNumber 2 would show pic 3
}

function nextPicture(){
    if (picNumber < noOfPics){  // noOfPics rather than total number of pics in array so that more can be added and this number doesn't have to be changed each time.
    picNumber++
    }
document.after.src=myPic[picNumber-1]
}