Show html content when multiple selecting

Hi. I have this code:

<select id="select_preferences" multiple="multiple">
    <option value="Anerobic"> Do Anerobic Routines</option>
    <option value="Aerobic">Do Aerobic Routines</option>
    <option value="Diet">Diet Healthy</option>
</select>
<script type="text/javascript">
    $(document).ready(function() {
        $('#select_preferences').multiselect({
            buttonText: function(options, select) {
                return 'Look for users that:';
            },
            buttonTitle: function(options, select) {
                var labels = [];
                options.each(function () {
                    labels.push($(this).text());
                });
                return labels.join(' - ');
            }
        });
    });
</script>

Code (JavaScript):

I now want to show the user some html code/elements when he selects at least one option from the drop down. How should I do that?

 

here's an updated code:

<select id="select_preferences" multiple="multiple">
    <option value="Anerobic"> Do Anerobic Routines</option>
    <option value="Aerobic">Do Aerobic Routines</option>
    <option value="Diet">Diet Healthy</option>
</select>
<script type="text/javascript">
    $(document).ready(function() {
        $('range-slider').hide();
        $('#select_preferences').multiselect({
            buttonText: function(options, select) {
                return 'Look for users that:';
            },
            buttonTitle: function(options, select) {
                var labels = [];
                options.each(function () {
                    labels.push($(this).text());
                });
                $('item').show();
                return labels.join(' - ');
            }
        });
    });
</script>
<!-- html code & script for age-range selector -->

<input type="hidden" class="slider-input" value="23" />

<script>
    $(document).ready(function() {

$('.range-slider').jRange({
    from: 16,
    to: 100,
    step: 1,
    scale: [16,30,50,75,100],
    format: '%s',
    width: 300,
    showLabels: true,
    isRange : true
})});
</script>

Code (JavaScript):