Connecting the gateway that your business uses to process credit cards is a breeze.
From the left side navigation, click on Integrations and then click Payment Methods
Here you will enter a "friendly name" which is any name that means something to you. Then select the gateway type from the drop-down menu.
You will be prompted to enter your gateway user credentials. These credentials vary and may be an email address and password or an API key. When done, click the Add button.