Velocity Reviews - PHP MySQL UPDATE

Can anyone help me with correcting this page so it works?

Seems to have a problem with this line esp, $id=($_GET["id"]);

<?php
echo '<html>
<head>
<title>Edit a Record from MySQL Database</title>
</head>
<body>
<form method="post" action="update_ac.php">';
$con = mysql_connect("localhost","root","");
if (!$con)
{
die('Could not connect: ' . mysql_error());
}

mysql_select_db("my_db", $con);
// get value of id that sent from address bar
$id=($_GET["id"]);

// Retrieve data from database
$sql="SELECT * FROM persons WHERE id='$id'";
$result=mysql_query($sql);

echo "<table border='1'>
<tr>
<th>ID</th>
<th>Firstname</th>
<th>Lastname</th>
<th>Age</th>
</tr>";
while ($row = mysql_fetch_array($result)){
$id = $row['id'];
$FirstName = $row['FirstName'];
$LastName = $row['LastName'];
$Age = $row['Age']; //we will echo these into the proper fields
echo '<tr><td><input type="text" value="<?php echo $id;?>" name="id" disabled/><br/> </td
<td>First Name:<br/><input type="text" value="<?php echo $FirstName;?>" name="FirstName"/> <br/> </td
<td>Last Name:<br/><input type="text" value="<?php echo $LastName;?>" name="LastName"/> <br/> </td
<td>Age:<br/><input type="text" value="<?php echo $Age;?>" name="Age"/> </br>
<input type="submit" value="submit changes"/></td</tr>';
}
echo "</table>";
// close connection
mysql_close($con);
?>
<?php
echo "</form>
</body>
</html>";
?>