In order to accept payments through WorldPay on your website, you must first register for a WorldPay Account here.
To Process payment with your WorldPay Merchant account, you need the following things.
WorldPay Installation ID
Without the above Credentials, you will not be able to process live WorldPay Payments
B.) Setting Up and Testing the WorldPay Gateway
Login to your WorldPay Account. And click on Setup Tab at the Left Side
Here you will see the list of the Installations available for your account. Click on the Settings Icon under Integration Setup: TEST
Here you will find the Installation Id and the settings that need to be filled before Testing the Gateway. Payment Response URL will be <wpdisplay item=MC_callback> On this page you also need to set the MD5 secret for transactions and Payment Response password.
Below are step to add the files required for successful redirection back to the site to appropriate page depending on the status of the order.
On the Installations Page Click on Edit Payment Pages under Payment Page Editor
On Payment Page Editor screen select File Management