Can't get mail form to work

Hi,
I'm trying to develop a php employment application form, where users fill in information and the client receives an email with form fields filled out. I used CSS Form Builder, and although all the fields are there, when I click Submit, the page seems to process, but then nothing happens. I don't receive an email, nor does the sender receive acknowledgment (which is what I want). Also, the page should redirect to a thank-you or error page, but it simply goes back to the form page. I've tried looking up information in the how-to pages to find out what I'm doing wrong, but the problem isn't addressed.

I'm under deadline so really need an answer. I've attached the files in zip format. Thank you for whatever help you can offer. I'm new to php and so need to be walked through this step-by-step.

Thank you.
Dawn Boyer