To create a custom field, select New Field and enter the relevant information.

Field Title - Create a title for the field, in this example the field title is ID Number.
Field Title - Provide the field with a unique code.
Mandatory - By checking this field, the user will be forced to provide a value when completing the form.
Field Type - This allows you to choose between text, text area, password, list, date, time, url or numeric.
Field Options - When selecting the 'list' field type, this box allows you to define which fields will appear in the drop-down list. Each list item should be on a new line.
Order - This allows you to specify the order in which this field will appear on the form.
By checking the box at the bottom you allow your created custom field to be available to all users/clients.
When you are finished, select Save.