Description of form fields in MailChimp WordPress plugin.
After selecting MailChimp list(s) from List option, buttons indicating list fields will automatically appear right below. Clicking on those will add corresponding fields to your form.
You can also place Form Action field, which adds Subscribe and/or Unsubscribe options to your form. This way you can let your subscribers to choose whether or not to join your mailing list. Click on Form Action button to open field editor. Set a label for this field, select Option type, which can be radio button, checkbox or select box, and click Save.
Similarly, if you add List Choice field to your form, users can select the MailChimp list, to which they wish to subscribe.
Besides MailChimp form fields, the MailChimp WordPress plugin also allows you to place Custom Fields to your form. The data from these fields will not be transferred to MailChimp. However, it will be saved in Submissions page of the plugin.
For instance you would like to also have payment on your subscription form. Press Custom Fields button and open PayPal__section. There are six types of payment fields for selecting the amount or item to purchase, __Amount, Select, Checkbox and Radio button. Moreover, Shipping and Total fields can be added to calculate corresponding values. Choose the field you wish to place, edit its label from Field label option and click Save.
If you will need to remove a field, simply click on it once and hit the small X button above it. Furthermore, in case you wish to edit it instead, you can use the button with pencil icon or double click on the field.
After you are done making these changes, make sure to hit Save.