need to add to flat rate module

i'd like to add a few flat rate options to the flat rate module, i know it's a pretty basic module consisting of 2 files.

here is the code for the delivery.php file

define('MODULE_SHIPPING_DELIVERY_TEXT_TITLE', 'Courier Service ');
define('MODULE_SHIPPING_DELIVERY_TEXT_DESCRIPTION', 'Courier Service ');
define('MODULE_SHIPPING_DELIVERY_TEXT_WAY', 'Next Day Delivery up to 6:30pm (Winnipeg only)');
define('MODULE_SHIPPING_DELIVERY_TEXT_WAY2', 'Winnipeg over 25kgs ');
define('MODULE_SHIPPING_DELIVERY_TEXT_WAY3', 'Next Business Day Selkirk, Steinbach, Portage La Prairie ');
define('MODULE_SHIPPING_DELIVERY_TEXT_WAY4', 'Outside Winnipeg Over 25kgs');

now what do i add to the delivery.php file in includes/modules/shipping