Take part of URL, put into form, post to database.

$id = $_GET['id']; This is looking for a get variable with name='id'. Change
name="textfield"
to
name="id". I believe this will fix it.

Hi, thanks for your quick reply but I need the id to from the url to show in the text field so when I submit the form the id will post to the database. If it helps this is the code I'm using to submit the form and the form itself with the change advised from you.

<?php require_once('modulatemedia.php'); ?>
<?php
if (!function_exists("GetSQLValueString")) {
function GetSQLValueString($theValue, $theType, $theDefinedValue = "", $theNotDefinedValue = "") 
{
  $theValue = get_magic_quotes_gpc() ? stripslashes($theValue) : $theValue;

  $theValue = function_exists("mysql_real_escape_string") ? mysql_real_escape_string($theValue) : mysql_escape_string($theValue);

  switch ($theType) {
    case "text":
      $theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
      break;    
    case "long":
    case "int":
      $theValue = ($theValue != "") ? intval($theValue) : "NULL";
      break;
    case "double":
      $theValue = ($theValue != "") ? "'" . doubleval($theValue) . "'" : "NULL";
      break;
    case "date":
      $theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
      break;
    case "defined":
      $theValue = ($theValue != "") ? $theDefinedValue : $theNotDefinedValue;
      break;
  }
  return $theValue;
}
}

// *** Redirect if username exists
$MM_flag="MM_insert";
if (isset($_POST[$MM_flag])) {
  $MM_dupKeyRedirect="register2.php";
  $loginUsername = $_POST['username'];
  $LoginRS__query = sprintf("SELECT username FROM members WHERE username=%s", GetSQLValueString($loginUsername, "text"));
  mysql_select_db($database_modulatemedia, $modulatemedia);
  $LoginRS=mysql_query($LoginRS__query, $modulatemedia) or die(mysql_error());
  $loginFoundUser = mysql_num_rows($LoginRS);

  //if there is a row in the database, the username was found - can not add the requested username
  if($loginFoundUser){
    $MM_qsChar = "?";
    //append the username to the redirect page
    if (substr_count($MM_dupKeyRedirect,"?") >=1) $MM_qsChar = "&";
    $MM_dupKeyRedirect = $MM_dupKeyRedirect . $MM_qsChar ."requsername=".$loginUsername;
    header ("Location: $MM_dupKeyRedirect");
    exit;
  }
}

$editFormAction = $_SERVER['PHP_SELF'];
if (isset($_SERVER['QUERY_STRING'])) {
  $editFormAction .= "?" . htmlentities($_SERVER['QUERY_STRING']);
}

if ((isset($_POST["MM_insert"])) && ($_POST["MM_insert"] == "form1")) {
  $insertSQL = sprintf("INSERT INTO members (firstname, lastname, username, password, email, recomendedbyid) VALUES (%s, %s, %s, md5(%s), %s, %s)",
                       GetSQLValueString($_POST['firstname'], "text"),
					   GetSQLValueString($_POST['lastname'], "text"),
					   GetSQLValueString($_POST['username'], "text"),
                       GetSQLValueString($_POST['password'], "text"),
                       GetSQLValueString($_POST['email'], "text"),
                       GetSQLValueString($_POST['recomendedbyid'], "int"));
  mysql_select_db($database_modulatemedia, $modulatemedia);
  $Result1 = mysql_query($insertSQL, $modulatemedia) or die(mysql_error());

  $insertGoTo = "stores.html";
  if (isset($_SERVER['QUERY_STRING'])) {
    $insertGoTo .= (strpos($insertGoTo, '?')) ? "&" : "?";
    $insertGoTo .= $_SERVER['QUERY_STRING'];
  }
  header(sprintf("Location: %s", $insertGoTo));
}
?>

<form id="form1" name="form1" method="POST" action="<?php echo $editFormAction; ?>">
  <label></label>
  <table width="241" border="0" align="center">
    <tr>
      <td colspan="2"><h2 align="center" class="style4">Registration</h2>        </td>
    </tr>
    <tr>
      <td width="79"><span class="style3"><strong>
        
      </strong>        
        
      </span>        <span class="style2">
     
      </span>      <div align="right" class="style3"><strong>*Username:</strong></div>      </td>
      <td width="152"><input name="username" type="text" id="username" tabindex="1" maxlength="20" /></td>
    </tr>
    <tr>
      <td><span class="style3"><strong>
       
      </strong>        
        
      </span>        <span class="style2">
      
      </span>     <div align="right" class="style3"><strong>*Password:</strong></div>      </td>
      <td><input name="password" type="password" id="password" tabindex="2" maxlength="20" /></td>
    </tr>
    <tr>
      <td><span class="style3"><strong>
        
      </strong>        
       
      </span>        <span class="style2">
     
      </span>      <div align="right" class="style3"><strong>*Email:</strong></div>      </td>
      <td><input name="email" type="text" id="email" tabindex="3" maxlength="50" /></td>
    </tr>
    <tr>
      <td class="style3"><div align="right"><strong>*Firstname:</strong></div></td>
      <td><input name="firstname" type="text" id="firstname" tabindex="3" maxlength="50" /></td>
    </tr>
    <tr>
      <td class="style3"><div align="right"><strong>*Lastname:</strong></div></td>
      <td><input name="lastname" type="text" id="lastname" tabindex="3" maxlength="50" /></p></td>
    </tr>
    <tr>
      <td><div align="right">*Referal ID</div></td>
      <td><?php $id = $_GET['id']; ?>
        <input type="int" name="id" id="textfield"?></td>
    </tr>
    <tr>
      <td>&nbsp;</td>
      <td><input name="submit" type="submit" id="submit" tabindex="4" onclick="MM_validateForm('username','','R');MM_validateForm('password','','R');MM_validateForm('email','','RisEmail');return document.MM_returnValue" value="Register" /></td>
    </tr>
    <tr>
      <td>&nbsp;</td>
      <td><span class="style7"><a href="file:///C|/Users/Up Stairs/Desktop/login script/login.php">login</a></span></td>
    </tr>
    <tr>
      <td>&nbsp;</td>
      <td><span class="style7">*required fields</span></td>
    </tr>
  </table>
  <input type="hidden" name="MM_insert" value="form1" />
</form>

Thanks again for the help.

Ok, so it should be name="recomendedbyid" and not name="id". Just skimmed over the code.

You are an absolute star that works fine and such a simple fix, always learning.
One last thing on this, do you know a way to shade out the textfield so the id that has been echo'ed back can't be typed over.

Once again many thanks.

shade out ? You mean read only ?
<input type="text" name="id" readonly>