Is this a static website? When you fill out and submit the form, what code do you have that receives and processes said form? You indicated that you built this with CSS and HTML, but those aren't server languages. Is there something else that you are using to process the submitted form? Do you use some third party service to do that? What would be helpful is a technical explanation of what you are trying to do.
OK. You should update the original question you asked to include the fact that the server side code is using PHP and you'll probably get more targeted responses. Also, which database are you using and where is that being hosted?
