collecting email address from user input textbox

I am confused on how this works.  Can someone please explain?  I want to build a contact us page with textboxes for "your name', "your email", and "comments".  Here is a code snippet I found on one of the posts:
MailMessage message = new MailMessage();
            message.From = new MailAddress("myemail@domain.com");
            message.To.Add(new MailAddress("someone@domain.com"));
            message.Subject = "Test";
            message.Body = "This is a test message";
            message.IsBodyHtml = false;
How do I alter this code to accept and send t ...