<style>
  div {background: green; color: yellow; cursor: pointer}
</style>

<select id="sel">
  <option>1</option>
  <option>2</option>
  <option>3</option>
  <option>4</option>
</select>

<div id="myDiv">
  <div>first content</div>
  <div>second content</div>
  <div>third content</div>
  <div>fourth content</div>
</div>

<script>
(function wizard() {
var div = myDiv.getElementsByTagName('div');
var dl = div.length;

  div[0].style.display = 'block';

  for (var i = 1; i < dl; i++) {
    div[i].style.display = 'none'
   }

var curIndex = 0;

  sel.onchange = function () {
    var index = sel.selectedIndex;
    div[index].style.display = 'block';
    div[curIndex].style.display = 'none';
    curIndex = index;
  }

})();
</script>