Here is the way to add and configure an Authorize.net Payment Form method to WordPress website mostly using woo-commerce plugin. Here is one of the plugin Authorize.net Payment Gateway For WooCommerce that help to add authorize payment method to website....
How to add an Authorize Payment method to WP website
How to get Transaction and Signature key in Authorize account ?
Steps to get Login ID and Transaction Key and Signature Key from the Authorize account. 1) Login to your Authorize.net account. 2) Click on Settings from the left panel. 3) After this click on API Credentials & Keys like link...