If you would like to use security on a single form and not all of the Forms of a template type, you can do this when you have filled out the sections of the form you would like filled, selected the checkbox beside 'Convert to Webform?' and then Save the form.
The saved form will now have the Webform Security options to select from.
Inherit from Template applies the security setting that you have for the Form Template.
Anyone with Link means anyone with the link to the Webform can view and submit the form.
Password Protected will require the person submitting the form to enter a password in order to do so.
SMS/Email Verification will send a code to the mobile device or email address of the intended party who should be submitting the form.