Go to the Lists menu, choose Custom Lists and Field Names and then choose the card type for which you want to set up a custom field, for example, Customers. The Custom List and Field Names window appears.
Type the names of the custom fields you want to set up for the card type you have selected in the Name of Custom Field fields. For example, you could enter ‘Birthday’ to record your contacts’ birthdays.
Click OK. The custom field names you entered will now appear in the Card Details tab of the Card Information window.