Pass a variable to another page - PHP

I have 2 PHP files:

send_data.php = has a form, and in the PHP section of the page I declared two variables that are used in the script. when user clicks SUBMIT it takes the user and the info INSIDE the form to receive_data.php

received_data.php = received the information that was submitted in the form inside send_data.php, but cannot use the variables that weren’t declared in the form.

How can I declare variables in a file and then use the variables in another file. (The variables are not declared in the form)???

SEND_DATA.PHP

<?php
$edit_table=$_POST[‘edit_table’];

if ($edit_table == super)
{
echo(“EDITING MESSAGE”);
$ID = ‘11’; <<<<<< THIS IS THE VARIABLE I WANT TO USE IN RECEIVE_DATA.PHP

$sql_body = “SELECT body FROM $edit_table WHERE id = $ID”;
$result_body = mysql_db_query(‘content’, $sql_body);
$row_body = mysql_fetch_array($result_body);
$body = $row_body[“body”];
?>

<form action=“receive_data.php” method=“post” name=“edit_message”>
<p>Edit:</p>
<textarea name=“content” cols=“70” rows=“20” wrap>
<?php echo $row_body[“body”]; ?>
</textarea>

<p>
<input type=“submit” name=“submitContent” value=“SUBMIT” />
</p>
</form>