How can I add a quick validation to this code:

[Padgoi]

The current code is:

 

<?php


$errors = array(); // set the errors array to empty, by default
$fields = array(username, profile,registration); // stores the field values
$message = "No!";

mysql_select_db("table", $con);


$sql="INSERT INTO Ratings (username, profile, registration)
VALUES
('$_POST[username]','$_POST[prof]','$_POST[registration]')";

if (!mysql_query($sql,$con))
  {
  die('Error: ' . mysql_error());
  }
echo "Your information has been added to the database.  Please choose an option below.";

mysql_close($con)
?>

 

I need to make it so people can't put iframes or anything and so that there is a limit of 60characters in each field.  Any help would be greatly appreciated. 

[Padgoi]

Any help please?