Just for fun, I've translated your asp (which isn't particularly well written) to (decent) php. this should make things very simple for you.
<?php
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
include 'include/myConn.asp';
if (mysql_connect('hostname','username','password') {
mysql_select_db('databasename');
} else {
trigger_error(mysql_error());
}
$id = mysql_real_escape_string($_POST['id']);
$myTitle = mysql_real_escape_string($_POST['myTitle']);
$myDesc = mysql_real_escape_string($_POST['myDesc']);
$myHeader = mysql_real_escape_string($_POST['myHeader']);
$mySubHeader = mysql_real_escape_string($_POST['mySubHeader']);
$myPageData = mysql_real_escape_string($_POST['myPageData']);
$sql = "
UPDATE myAbout
SET
myTitle = '$myTitle',
myDesc = '$myDesc',
myHeader = '$myHeader',
mySubHeader = '$mySubHeader',
myPageData = '$myPageData'
WHERE id = $id
";
if (mysql_query($sql) && mysql_affected_rows()) {
header('Location: update-success.php');
} else {
header('Location: update-failed.php');
}
}