Setup within Kartris | kartrisguide

Go to Configuration > Payment and Shipping Gateways and click to edit 2Checkout.
For 'friendly name', you can enter '2Checkout', or just simply 'Credit Card'. This is just the name of the payment method that customers will get to choose on the web site during checkout if you have multiple payment methods.
Change the status from 'OFF' to 'ON' (for live orders) or 'TEST' or 'FAKE' for testing. 'TEST' invokes a demo order, allowing you to test the full integration and pass multiple orders at zero cost without needing to do refunds. 'FAKE' means that Kartris will skip the 2Checkout site and instead format a post back itself to the callback page of Kartris. This is useful for testing that the callback process works, triggers the appropriate emails and so on without keep having to keep going through the 2Checkout payment process.
Set your 'SID', which is the vendor number assigned to you by 2Checkout.