When logged into Gunbroker.com, select ‘Toolbox’ in the lefthand menu. From there, click the ‘View’ button next to ‘Checkout Setup’.
Edit Your Payment Gateway
In the Checkout Setup screen you will see an item called ‘Payment Gateways’. Click the ‘Edit’ button next to this item to start setting up your gateway.
Under ‘Payment Gateway’, select Authorize.net
Under ‘Transaction Type’, select ‘Authorization and Capture’.
Under ‘Authorize.net API Login’, enter your API login credentials.
Confirm the credentials in the ‘Confirm Authorize.net API Login’ section.
Under ‘Authorize.net Transaction Key’, input your transaction key.
Confirm the transaction key in the ‘Confirm Authorize.net Transaction Key’ section.
Enter your cash discount percentage. Most merchants put 3%, although you are not required to input an actual discount, 0 is also acceptable.
Save Changes And Test Your Gateway
Click the ‘Save All Changes’ button to save your changes. Any errors in the setup will be shown to you. If there are no errors, test your gateway.