How do I set a Next URL or "Thank you" page for users submitting the form?

How do I set a Next URL or "Thank you" page for users submitting the form?

To set up the Next URL:
  1. Go to Forms.
  2. Select the intended form from the list of forms.
  3. Click Customize Form.
  4. In Form Properties, 
  5. Click Choose Action under submit action.
  6. Select Web URL to add an external url. Or click Page and select the intended page from the list of pages in the drop down.
  7. Click Save.
To create a Thank You page, refer here.