I'm getting this error:

 Parse error:  syntax error, unexpected ':' in /home/xxxxxxxx/public_html/redirect.php  on line <b>3

this is my code:

PHP Code:

<?php

   header( 'Location: $_GET["url"] ') 

?>

what am I doing wrong? Thanks!

Two things I see wrong:
1. You forgot to add a semi-colon at the end of the line.
2. If you want variables in a string to be parsed you need to use double quotes

Neither of these things should cause the error you mentioned however.

Try:

PHP Code:

<?php

   header('Location: ' . $_GET['url']); 

?>