Getting jsfiddle 'show image file' working

I've sure I'm missing something simple here, I found a suggestion on here to use jsfiddle for code to preview an image before upload: http://ift.tt/1GlwJ6O

But I can't get it to work. I'm assuming I just put the javascript in the header wrapped in tags?

Here's my code (thank you - I'm sorry if this is very similar to other questions)

        <script language="javascript">
                window.onload=function readURL(input) {
                        if (input.files && input.files[0]) {
                                var reader = new FileReader();
                                
                                reader.onload = function (e) {
                                        $('#artworkshow').attr('src', e.target.result);
                                }
                                
                                reader.readAsDataURL(input.files[0]);
                        }
                }
                
                $("#artwork").change(function(){
                        readURL(this);
                });
        </script>

                            <img id="artworkshow" src="#" alt="Image Preview" />
                                <p>
                                        <label for="artwork">Artwork</label>
                                        <input id="artwork" name="artwork" type="file" class="inputAuto" />
                                        Size: 700px by 260px</p>
                                <p>