web programming question?

You'll want to be extremely careful in what you allow your users to do in terms of their pages. If you give users ability to create pages using full html and javascript access you could have a cross site scripting hack in no time. Since you're new to PHP you'll best want to strip all but the most essential html tags (like <b>,<i>,<u>)

Yes, its possible in PHP

you can download the source code from joomla website http://joomla.org

with regards,
A Suresh Kumar
http://suresh-mobileweb.blogspot.com

The easiest is to download a script and play with it (tweak/customize it so that it's what you need).

http://www.hotscripts.com/PHP/Scripts_and_Programs/User_Management/index.html

It is not that simple I am afraid. Yes, PHP is used to create it, but you will need moderate programming expertise to do this.