FreshSpoke is a great tool to manage your customers and communicate with them on regular basis. You can import customers in a batch or one at a time. Simply click the menu tool to the right of the search box on your customer tab as shown in the image below. 

Referring to the screen above, note the red icon. This indicates that your customer has not set up an account on FreshSpoke so there are no credit terms available to this customer. Therefore you must have their credit card information on hand in order to use FreshSpoke's payment gateway for this customer's orders. If the customer is a registered FreshSpoke buyer that has been approved for credit terms, this along with a credit card option is available at check out.  

For customers with whom you have a trusted financial relationship, you can opt to manage the payment yourself by switching from 'pay at checkout' to 'pay you later'. The invoice your customer receives will specify your business as the payee along with any other payment information you have assigned to that customer such as payment terms, vendor #, etc.