You will need to have registered an account with USPS at http://www.uspsprioritymail.com/et_regcert.html to use this module

USPS expects you to use pounds as weight measure for your products.'); define('MODULE_SHIPPING_USPS_TEXT_OPT_PP', 'Parcel Post'); define('MODULE_SHIPPING_USPS_TEXT_OPT_PM', 'Priority Mail'); define('MODULE_SHIPPING_USPS_TEXT_OPT_EX', 'Express Mail'); define('MODULE_SHIPPING_USPS_TEXT_ERROR', 'An error occured with the USPS shipping calculations.
If you prefer to use USPS as your shipping method, please contact the store owner.'); ?>