How to populate text field information?
If you have set up your Custom Field as a text format then you can enter text into the custom field column heading that matches your custom field heading inside your account.
Please see below an example of a Custom Field text format heading called 'More info?':
Please see below the Custom Field heading 'More info?' on the Excel sheet:
Here you can enter the text into each cell for the relevant contacts, when this text data is imported into your account it will update your contacts as shown below: