You need to start with programming 101. Having somebody teach you how to program a database-driven account login application via instant messaging is NOT a place to start.
You will need a webserver, a database server, a programming language or two, and proficiency in all the above. One of your first tasks is to choose which architecture you want to learn. Do you want to do things the Microsoft way using Windows, IIS, ASP.NET, C#, SQL Server? Or would you rather use Linux, Apache, PHP, and MySql. Perhaps you want to use Solaris, Tomcat, and Java? Perhaps some combination of the above?
As a newbie wanting to get into building data-driven web applications, I strongly recommend PHP and MySql. I come from the Microsoft way and am an expert ASP/SQL Server developer so I know a little about what I'm talking about. I don't know anything about Tomcat or Java so I can't say although it's safe to say that Java is definitely not a beginner's programming language or for the faint of heart.
If, after your own research, you decide PHP is your choice, head over to http://www.php.net/tut.php and start the journey. This tutorial will teach you a lot. It will teach you that you need a webserver that is configured to process PHP scripts. If you use a Windows computer at home like most people, then I recommend you install Apache Webserver on your computer then install PHP and configure Apache to load the PHP module. Then install MySql and setup a database to work with. If that sounds difficult and confusing, well, it is--when you are starting out. That's why I'm trying to tell you that you have a LONG way to go and a few hours of instant messaging aint gonna get you where you want to be.
START with the PHP beginner tutorials to get oriented. Then you may find my WAMP HOWTO to be useful. WAMP stands for Windows, Apache, MySql, and PHP. Those four pillars create the foundation for building about any Internet application you can dream up.
Once you learn this stuff and you are ready to launch a website into production for thousands of users, I recommend you use Linux as your webserver. No need to debate that topic in this thread (PLEASE), but research a little and you will figure out why I recommend this.
I wish you success on your journey. It is a rewarding journey for those with enough self-discipline to master the art.