Not sure I follow - that query is correct, you can't do that with just PHP, you need to actually connect to a database send the query to the database. But if you're wanting to do it via ubbthreads, the script would:
- Need to include the library by including main.inc.php (so that it connects to your database, and knows all your database settings.
- Need to have a call to do_query (to actually perform the query).
Example for a 6.5.x forum:
<br /><?<br />require("./includes/main.inc.php");<br /><br />$query = 'update w3t_Users set U_Signature = "<img src=http://www.myboard.com/ubbthreads/uploads/picture.jpg>" where U_Username = "troublemaker"';<br /><br />$dbh -> do_query($query,__LINE__,__FILE__);<br /><br />?><br />