After you get your credentials from your credit card processor, you'll need to enter that info into Birddog's credit card system.
This can be accomplished in your website's dashboard. Go to Dashboard>System Management>System>Payment Gateways. Click on the "Add" icon and enter your info. Note that when you change the Gateway DDL, some of the required information will alter according to the gateway.
Using Enterprise for Windows
Credit Card Accounts – Merchant Number is an auto-assigned (on the website; you can manually set this number in Enterprise for Windows as noted below.) This number must be unique for all merchant accounts. LoginID and Password are the LoginID and Password assigned by the gateway; note that the labels for these may change according to the merchant account. Authorize.net, for example, has Transaction Key instead of Password, but they're the same thing in this context. Consult support with any confusion.
You can also setup your payment gateways in Enterprise for Windows. Go to Maintain>Credit Cards>Merchant Accounts. Below are screen shots from Enterprise for Windows.
Gateway Address and Port are to be used for this gateway if other than default. Gateway is the gateway to use for this merchant account.