Help setting up custom e-commerce connection to My.Shiprush

Hi
I am trying to set up a connection from my custom e-commerce site to shiprush.
I did get ShippingZSimulator.php working but can't get my own php to work.

Questions
1. where do I tell shiprush about my database?
In example files I see:
$cart_db_link = mysql_connect($db->host, $db->user, $db->password) OR die(mysql_error());
but don't see where host, user, password get set.

2. where do all of these get set?
TABLE_ORDERS, TABLE_ORDERS_STATUS_HISTORY, DB_PREFIX

Thanks for any help!!
Genelle