How can I password protect a form?

I assume you meant you just want to add password / access code to access section/elements of your form. You can refer to this similar discussion thread for guide.

https://www.jotform.com/answers/1370112-How-to-set-a-password-for-my-form

But do take note that this method is not securing the form. Any person with understanding on how to read source code can figure out what is the password/access code of the form.

To make your form secure you can refer to this article: JotForm Secure Online Forms

I hope this help. Let us know if you require further assistance.