The default action for the form in CSS Form builder is to post to itself.
This is the simplest way to set it up.
The action page is where CSS Form builder will place the code to process the server validations for the form.
If you want to have the form contents sent to you in an email, you can set that up on the Form Functions page
after the form is created, you can edit the Universal Email server behavior to set it to redirect to another page after sending the email.