Sometimes the fields that come as default for lists just don't quite cut it for what you need. Luckily you can add your own fields to the list so you can collect and store the info best for your business.
To create your own field click the Account icon in the top right of the tool bar - it looks like a person - then select Custom Fields from the menu that appears.
There are twenty fields here that you can set up for whatever you need. Just click in one of the boxes and add your field name. It can be anything that works for you, just keep it to letters, numbers and spaces, no symbols please. Once you've added your new fields click the Save button in the top left corner to save your changes. And voila! Your lists contact details will now have the new field listed at the bottom of the page.
You can also create a custom field during your list upload. On the Map Fields page just type in a new custom field name where it says Unmapped. In the window that pops up type in the new field name and click Create to save it.
While you can add custom fields manually or when uploading a list, you cannot include them on sign-up forms or landing pages at this time. You can add that information either through a new list upload, or by inputting it manually in each contact.