In order to make the form secure you should be applying the validations from within the Form Builder wizard.
CSS Form Builder will create the forms for you but does not add in the email functionality. This is handled by our Universal Email tool. You can just apply it directly onto the page that the form is on. When configuring it you can just use the lightning bolt icons to select the form elements that those values should come from, like the 'to' email address. There is a bit more info on setting up Universal Email and configuring the server behavior on the Universal Email support page.