To add a Field to a Resource Type, simple select the Field Type from the dropdown menu and click on the "Add Field" button.
Text and Textarea Fields: When you select to add them, the UI will prompt you to provide a Name/label for the new field.
Choicebox Fields: When you select a Choicebox field, you will prompted to enter the Options that should appear in the dropdown menu. You can continue adding options using the "Add Option" button.
Once fields are added to a Resource Type, you can use the "Edit" and "Remove" links for each field to make any additional changes to the fields.