SQL queries in vBulletin

[stephenNYC]

Hi, I've looked at a lot of postings here and suspect I am being dense, but I am not quite understanding some things and need a little help.
I added a table (cNews) to my vBulletin db and wrote a php page to INSERT or SELECT but need some help integrating and then calling the variables ($num, $headline, $news) in throughout the site.

I read Brad's 'vBulletin and mySQL' article (https://vborg.vbsupport.ru/showthread.php?t=75207) but still don't where and how to write SELECT, INSERT and UPDATE statements,

Thanks very much
Stephen

Here's my code.

$conn = mysql_connect($server, $userName, $password) or die(mysql_error());
mysql_select_db($db_name,$conn) or die(mysql_error());

$postback = $_POST["postback"];
if (empty($postback)) { //no new input so get last
$sql="SELECT num, headline, news FROM cNews ORDER BY num DESC LIMIT 1";
$result = mysql_query($sql, $conn) or die(mysql_error());
}
else { //insert new data then get last
$headline = $_POST["headline"];
$news = $_POST["news"];
$sql = "INSERT INTO cNews VALUES (num,'".$headline."','".$news."')";
$result = mysql_query($sql, $conn) or die(mysql_error());
$sql="SELECT num, headline, news FROM cNews ORDER BY num DESC LIMIT 1";
$result = mysql_query($sql, $conn) or die(mysql_error());
}

while($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
$num = $row['num'];
$headline = $row['headline'];
$news = $row['news'];
}