What type of control are you looking for to capture the additional data. If you need a textbox, you could use the comments fields which is a multiline textbox. To use the comments field as a regular textbox you would need to edit the step1.ascx and delete the textmode="multiline" and change the label to whatever label you want. The following are the custom fields that are availible on the step 1 page which is the first page of the payment registration:
User Entered Amount
Check this box if you want the user to be able to enter an amount in the registration amount field. This is useful for sites that collect donations and allows the user to enter any amount they wish to donate.
Show Quantity
Check this box if you want the user to be able to enter a quantity in the registration. This is useful for sites that sell tickets to events or if you want the user to enter a quantity for the product or service you are selling.
Show Invoice#
Check this box if you want the user to be able to enter their invoice number. This is useful if you are using the module for customers to pay their invoices online.
Custom Listbox
Show Listbox - When show listbox is checked, a listbox will be displayed on step 1 of the payment form. The user defined listbox is useful for adding terms and conditions or custom content to your payment form.
Listbox Label – The Listbox label is the label that is displayed next to the custom list box displayed on the step 1 page.
Listbox Text – The Listbox Text is the text that is displayed in the custom list box displayed on the step 1 page.
Custom Checkbox
Show Checkbox - When the show checkbox is checked, a checkbox will be displayed on the step 1 page of the payment form. The checkbox is useful for opt in marketing like adding a user to your email list or can be used to require the user agree to the terms and conditions displayed in the list box described above.
Checkbox Label – The checkbox label is the label that shows up next to the checkbox described above.
Checkbox Required – Check this box if you want to make the checkbox required before the user can proceed to the next screen and make payment.
Custom Dropdown list
Show User Defined Field – When the show user defined field checkbox is checked a custom dropdown box will be displayed in Step 1 of the registration. The user defined dropdown box is useful in a variety of applications and will not be displayed to the user unless the checkbox is checked. For example, you could create a user defined dropdown called “How did you hear about us” with dropdown values of Internet, Yellow Pages, or Referral. The option selected by the user in the dropdown during registration is stored in the database for your to reference at a later time.
Dropdown Datasource – There are two options available for configuring the values in the dropdown; User entered Values and User entered SQL.
User entered values – When you select user entered values you will be able to type the values entered directly into the dropdown values textbox.
User entered SQL – When you select user entered SQL you will be using the native DNN Lists to populate the values in the dropdown. If you are not familiar with DNN Lists feature, login as host and navigate to the hosts – lists menu where you will be able to create your custom list. Once you have built your list using the DNN lists feature then you can enter a simple SQL statement to query the list and populate the datasource for your custom dropdown box.
Dropdown Label – Dropdown label is the label that shows up in the registration to the left of the custom dropdown box.
Custom Comments field
Show Comments Field – When the show comments field checkbox is checked a comments field will be displayed in Step 1 of the registration. The comments field allows your users to enter comments. The comments field is stored in the database for you to reference at a later time.
Show Coupon
Check this box if you want to offer your customer the ability to enter a coupon and receive a discount on their payment. If you check this box a coupon text box will be displayed on step 1 of the payment form for the user to enter their coupon code. If the user enters a valid coupon code their payment total will be discounted by the amount or percentage of the coupon that you configured in the Manage Coupons section.
For screen shots of the module settings where you configure these fields see the following link:
http://www.smith-consulting.com/products/dotnetnukemodules/registrationmodules/registrationpromodulesettings.aspx