Contact Form & Formmail Script
A contact form needs some html, and css to style it, along with a formmail script on your server to process the form info.
Here's a link to a well designed form by a master of CSS...
http://css-tricks.com/nice-and-simple-contact-form/
The form needs a method and an action.
<form method="post" action="http://domain-name.com/formmail.php">
As you can see, the action is the URL to the script on the server.
The contact form download mentioned above contains a php script which you can easily modify for your own use. It also has a script for a thank you message which acknowledges receipt of the message.
Alternatively, you can return visitors to a "thank you" page on your site - or any other page for that matter - by including this...
<input type="hidden" name="good_url" value="URL to the page" />
If you really don't want to get into all this you can use a form service. Google "website form service" to find all the usual suspects.