To add questions to your registration form please go to the Tickets portion on your dashboard > Question / Form > + Add Question. If you would like some questions only visible for certain types of tickets, please select the box that says "Show this question only for specific ticket types".
When your attendees go to register for the event, these questions will be within the registration form.
Once people start registering you can export your order responses to see their answers to your question form. To find this on your dashboard please go to the Attendees portion > Orders > scroll down to 'Download' > and click the blue 'Download List as Excel' button. You will see starting in column 'J' the questions and answers for each registrant.