Uploading file via PHP in form

Uploading file via PHP in form

(beginner)
I'm having trouble uploading my file. I see the filename being posted to
the database, but the file is not being posted to the images folder. It
seems as though nothing is happening. Here is my following code, please
advise me what I need to change:
<?php
//the $art variable gets posted to a database eventually
$art =
mysql_real_escape_string(stripslashes($_FILES["art"]["name"]));
$art_ext = $_FILES["art"]["type"];
$art = md5($art).$art_ext;
if($art!=""){
move_uploaded_file(md5($art).$art_ext, "images/");
}
?>
<script type="text/javascript">
$(function(){
image_upload = {
UpdatePreview: function(obj){
// if IE < 10 doesn't support FileReader
if(!window.FileReader){
// don't know how to proceed to assign src to image tag
} else {
var reader = new FileReader();
var target = null;
reader.onload = function(e) {
target = e.target || e.srcElement;
$("#imageupload").attr("src", target.result);
};
reader.readAsDataURL(obj.files[0]);
}
}
};
});
</script>
<form action="new.php" method="post" enctype="multipart/form-data">
<input type='file' name='art' id="file"
onchange='image_upload.UpdatePreview(this)' value="Upload"
accept="image/gif,image/jpeg,image/png"/>
</p>
<p>upload a image! (.gif, .jpg, .png formats allowed. 5MB max)</p>
<img id="imageupload" src="1x1.png" alt="test" />
<input type="submit" class="smallbtn4" style="cursor:pointer;" value="post"/>
</form>