How do people do this kind of scripts or html?

[A A]

Ok I was looking thourgh the Internet and was wondering wat is the script or html for this kind of site? I took a screenshot.http://i324.photobucket.com/albums/k350/super5cell/ads.png They have the box where you enter email and you get invite. I checked out the page source but I am not Getting it. Suppose I do something similar site and Someone writes their e-mail, where do I go to see thier e-mail? I'm a noob at these things. please give a step to step tutorial. thanks