Uploading af fil

Hej Eksperter!

Nu har jeg snart prøvet alt!!!
ka' sq ikke få det til at virke.
Hvad gør jeg galt!!??

Koden (fileupload.php):

<html>
<head>
<title>Fileform</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<body>

<?php
//dette er en masse tests!!
if($submit == "sendfile"){
        $filename=$_FILES['userfile']['tmp_name'];
    echo("file name: ".$filename);

    $filename = $_FILES['userfile']['name'];
    echo("file name: ".$filename);

    $filename=$HTTP_POST_FILES['userfile']['tmp_name'];
    echo("file name: ".$filename);

    $filename = $userfile;
    echo("file name: ".$filename);

    $filename = $userfile_name;
    echo("file name: ".$filename);
}
?>

<form enctype="multipart/form-data" action="<?echo $PHP_SELF;?>" method="post">
    <input type="file" name="userfile">
    <input type="submit" value="sendfile" title="Send file">

</form>
</body>
</html>