To enable this form, you need to add its name to the WEBFORMS field by editing WebPreferences (in your Wiki Web). Then, each time you edit a page, you will have the opportunity to add a form (there is a new button) from a list of forms and then input values for its fields.
Editing a form can only be done in a topic page. What is interesting is that we can use the Wiki topic page for capturing a discussion and the rationale for this requirement, on top of the form. The discussion can then be summarized by providing another search query. For instance: