JQuery - upload file with $.ajax [duplicate]

Possible Duplicate:
jQuery Ajax File Upload

i want to upload a file using php and during the upload i want to show a loader to the user. Afterwards one div should be changed, and therefore i thought jQuery will be the right choice.

I tried it with this method, but it is not working properly:

HTML:

<div id="pop_layerbody">
<form action="javascript:;" method="post" enctype="multipart/form-data" onSubmit="jsUploadFile();">
<input name="bild" id="bild" type="file" size="50" maxlength="100000">
<input type="submit" value="Hochladen" id="button_upload">
</form>
</div>

JavaScript/JQuery:

function jsUploadFile() {
    $('#pop_layerbody').html('<img src="../includes/images/ajax-loader-big.png" style="margin-top:35px;" />');
    $.ajax({
        type: "POST",
        url: "upload_picture_logic.php",
    }).done(function (msg) {
        alert("Data Saved: " + msg);
    });
}

PHP: (excerpt)

@move_uploaded_file($_FILES['bild']['tmp_name'], "upload/".$_FILES['bild']['name']);

Anybody know the answer? It seems that even the POST-combination between HTML and JS is not working...