Confused about an upload form script

I have the following code for an upload form. I am a bit confused as to what should be set for the destination of the upload. I realise that C:\data is a windows file system and I am currently testing it on OSX.


<?php 

/*Script name: uploadFile.php 
* Description: Uploads a file via HTTP using a POST form 
*/ 
if(!isset($_POST['Upload'])) 
{ 
    include("form_upload.inc"); 
} # endif 

else 
{ 
if($_FILES['pix']['tmp_name'] == "none") 
{ 
echo "<b>File did not successfully upload. Check the file size. File must be left than 500k.<br>"; 
include("form_upload.inc"); 
exit(); 
} 
if(!ereg("image",$_FILES['pix']['type'])) 
{ 
echo "<b>File is not a picture. Please try another file.</b><br>"; 
include("form_upload.inc"); 
exit(); 
} 
else 
{ 
    $destination = 'c:\data' . "\\".$_FILES['pix']['name']; 
    $temp_file = $_FILES['pix']['tmp_name']; 
    move_uploaded_file($temp_file,$destination); 
    echo "<p><b>The file has sucessfully uploaded:</b> 
    {$_FILES['pix']['name']} 
    ({$_FILES['pix']['size']})</p>"; 
    } 
    } 
    ?>

If I change c:\data to something like /library so that it is an OSX destination I get the following error -

Warning: move_uploaded_file(/Library\Picture 6.jpg): failed to open stream: Permission denied in /Library/WebServer/Documents/uploadFile.php on line 9

What am I doing wrong? Also if I wanted to change the code so that it uploaded to a server what would be the correct address (i.e ftp.hostname or IP address etc) to put for the destination? All I need is the file to upload to the same directory as this php file so does it need an address or will it upload to the same place as this script?