You can do something like this:
// set an active slide to display when page loads
$('.elem1').addClass('activeSlide');
// count your elements(which class name starts with "elem") and push them into an array
var
elems = 0,
i = 1;
$('[class^="elem"]').each(function(){
elems +=1;
});
// display one element at a time, by modifying the z-index value
$('.button').on('click', function(e){
e.preventDefault();
i+=1;
if(i > elems ){ i = 1; };
$('[class^="elem' + i + '"]').addClass('activeSlide').siblings().removeClass('activeSlide');
});
Example here: http://jsfiddle.net/WrQ4L/1/
Keep in mind that this method requires to have class names numbered ascending(the initial value of "i" is equal to the first class number -> elem1)