Hyperlink Click

I've been using PHP for some time now and have noticed the big difference between asp and php. In php i have been using this code

<?PHP
if (!isset($_GET['p'])) { // no page specified -> load content from default.txt
include("includes/center.php");
} else { // page specified -> load content from relevant text file
include("./" . $_GET['p'] . ".php");
}
?>

so for example if i clicked on the hyperlink that had this value "index.php?p=member" it will open (preferrably include) the member.php page onto the index.php page. How would this script be written in ASP?