If you don't already have a PayWhirl account you can start by installing the app. If you already have an account you can
Next fill out your PayWhirl application to create your PayWhirl account
With Shopify billing you won't have to enter another payment method. All monthly charges are billed directly to your Shopify account. If you are using Braintree or Authorize the transaction charges also billed to your Shopify account. This transaction charge is added to your monthly invoice. There is no contract so you can adjust your plan at any time.
Note: While you can use PayWhirl "inside of Shopify", it is recommended to open PayWhirl in a separate window or browser tab by going to PayWhirl.com directly.
When you select a paid monthly plan, you will be asked to approve the charge in Shopify. Click "Approve Charge" to continue.
That's it! You have successfully upgraded! Your Shopify account will be billed automatically for the application charges. If you just created a paywhirl account and are still on a free trial, the PayWhirl monthly plan charges will be billed to your Shopify account after the free trial expires. During that free trial period, PayWhirl and gateway transaction processing charges still apply.
You can now start configuring PayWhirl to process recurring payments. Check out this Shopify guide for help getting setup.
Please let us know if you have any questions.